The word ''praying'' in Quran

It has been expressed from the prophet (peace of Allah be upon him and his descendants) '' moan for your needs from God, resort to him in unpleasant events and call him because praying is brain of worshipping''.
When a person praying, it is the most sincere condition of persons because he or she is out of thoughts and guesses and there are no intermediates and causes between them and their God.
As it can be understood from the following verses, praying means worshipping;
فَادْعُوا اللَّهَ مُخْلِصِينَ لَهُ الدِّينَ وَلَوْ كَرِهَ الْكَافِرُونَ
Call ye, then, upon Allah with sincere devotion to Him, even though the Unbelievers may detest it .
وَلَا تُفْسِدُوا فِي الْأَرْضِ بَعْدَ إِصْلَاحِهَا وَادْعُوهُ خَوْفًا وَطَمَعًا ۚ إِنَّ رَحْمَتَ اللَّهِ قَرِيبٌ مِّنَ الْمُحْسِنِينَ
Do no mischief on the earth, after it hath been set in order, but call on Him with fear and longing (in your hearts): for the Mercy of Allah is (always) near to those who do good.
فَاسْتَجَبْنَا لَهُ وَوَهَبْنَا لَهُ يَحْيَىٰ وَأَصْلَحْنَا لَهُ زَوْجَهُ ۚ إِنَّهُمْ كَانُوا يُسَارِعُونَ فِي الْخَيْرَاتِ وَيَدْعُونَنَا رَغَبًا وَرَهَبًا ۖ وَكَانُوا لَنَا خَاشِعِينَ
So We listened to him: and We granted him Yahya: We cured his wife´s (Barrenness) for him. These (three) were ever quick in emulation in good works; they used to call on Us with love and reverence, and humble themselves before Us.
فَاسْتَجَبْنَا لَهُ وَوَهَبْنَا لَهُ يَحْيَىٰ وَأَصْلَحْنَا لَهُ زَوْجَهُ ۚ إِنَّهُمْ كَانُوا يُسَارِعُونَ فِي الْخَيْرَاتِ وَيَدْعُونَنَا رَغَبًا وَرَهَبًا ۖ وَكَانُوا لَنَا خَاشِعِينَ
So We listened to him: and We granted him Yahya: We cured his wife´s (Barrenness) for him. These (three) were ever quick in emulation in good works; they used to call on Us with love and reverence, and humble themselves before Us.
ادْعُوا رَبَّكُمْ تَضَرُّعًا وَخُفْيَةً ۚ إِنَّهُ لَا يُحِبُّ الْمُعْتَدِينَ
Call on your Lord with humility and in private: for Allah loveth not those who trespass beyond bounds.
قَالَ رَبِّ إِنِّي وَهَنَ الْعَظْمُ مِنِّي وَاشْتَعَلَ الرَّأْسُ شَيْبًا وَلَمْ أَكُن بِدُعَائِكَ رَبِّ شَقِيًّا
Praying: "O my Lord! infirm indeed are my bones, and the hair of my head doth glisten with grey: but never am I unblest, O my Lord, in my prayer to Thee''.
Allame Tabatabaei says '' worshipping is pillars of praying and manners of someone that worships. These manners include sincerity in worshipping and resorting only to God. Fear, hope, modesty, persisting, right deeds, faith in God and other matters mentioned in narrations are considered as worshipping''.
وَإِذَا سَأَلَكَ عِبَادِي عَنِّي فَإِنِّي قَرِيبٌ ۖ أُجِيبُ دَعْوَةَ الدَّاعِ إِذَا دَعَانِ ۖ فَلْيَسْتَجِيبُوا لِي وَلْيُؤْمِنُوا بِي لَعَلَّهُمْ يَرْشُدُونَ
When My servants ask thee concerning Me, I am indeed close (to them): I listen to the prayer of every suppliant when he calleth on Me: Let them also, with a will, Listen to My call, and believe in Me: That they may walk in the right way.
Allame Tabatabaei says according to the above verse '' God has considered him as his real owner and since they are his persons, he is close to them absolutely, closer than anything or someone to them''.
Quran states about worshipping
وَآتَاكُم مِّن كُلِّ مَا سَأَلْتُمُوهُ ۚ وَإِن تَعُدُّوا نِعْمَتَ اللَّهِ لَا تُحْصُوهَا ۗ إِنَّ الْإِنسَانَ لَظَلُومٌ كَفَّارٌ
And He giveth you of all that ye ask for. But if ye count the favours of Allah, never will ye be able to number them. Verily, man is given up to injustice and ingratitude.
يَسْأَلُهُ مَن فِي السَّمَاوَاتِ وَالْأَرْضِ ۚ كُلَّ يَوْمٍ هُوَ فِي شَأْنٍ
Of Him seeks (its need) every creature in the heavens and on earth: every day in (new) Splendour doth He (shine).
Some needs from God are not accepted because persons are ignorant toward their need, or their need is asked not only from God like a person that has a need from God, but he or she tends to other affairs and means. In fact, his or her praying had not been for God sincerely and had not summoned him. Hence, God that accepts needs of persons is creator that has no partners and does act though causes.
Prophet (peace of Allah be upon him and his descendants) states '' if you have a need, ask it from God and if you need help, as it from God''. It has been said in Ghodsi Hadith '' a devout person has only good guesses about me''. Therefore God is source of Goodness and persons need this goodness regularly. Praying is means so that persons can achieve higher rank and it is effective in descending of blessings and bliss of God. Imam Ali (peace be upon him) explains goodness and value of praying. It is said '' the best praying is that grieves are provoked by it''. Prophet (peace of Allah be upon him and his descendants) states '' God does not accept praying of someone that has heart without paying attention to God''.
Imam Ali (peace be upon him) was asked '' how far is between the sky and the earth?'' he answered '' it is as far as praying of an innocent person''. It means that tyranny should be removed from an innocent person and it should come back tyrant person. Therefore, need of such a person is accepted. Moreover, it represents that God is not far from aspect of place and is beyond place and time. In fact, made aspect of human imagination is his sins and deviations that have made him or her get away from God and his or her need is not accepted. Prophet (peace of Allah be upon him and his descendants) states '' purify your soul so that your need is accepted''. Therefore, money that is earned though illegal way causes that need is not accepted. It is narrated from Imam Ali (peace be upon him)
''اللَّهُمَّ اغْفِرْ لِیَ الذُّنُوبَ الَّتی تَهتِکَ العِصَمَ؛ اللّهُمَّ اغفِر لِیَ الذُنُوبَ الَّتى تُنزِلُ النِقَم، أللّهُمَ اغفِر لِىَ الذُنُوبَ الَّتى تُغَیِرُ النِعَم، أللّهُمَ اغفِر لِىَ الذُنُوبَ الَّتى تَحبِسُ الدُعَاءَ''
Imam Sadeq (peace be upon him) was asked '' why isn't our need accepted from God?'' he answered '' it is not accepted because you call someone that you do not know''. Therefore, recognition of God is one of causes and means that leads persons to pray and it facilities that need can be accepted.
Quran states
أَمَّن يُجِيبُ الْمُضْطَرَّ إِذَا دَعَاهُ وَيَكْشِفُ السُّوءَ وَيَجْعَلُكُمْ خُلَفَاءَ الْأَرْضِ ۗ أَإِلَٰهٌ مَّعَ اللَّهِ ۚ قَلِيلًا مَّا تَذَكَّرُونَ
Or, Who listens to the (soul) distressed when it calls on Him, and Who relieves its suffering, and makes you (mankind) inheritors of the earth? (Can there be another) god besides Allah? Little it is that ye heed.
أَيَّامًا مَّعْدُودَاتٍ ۚ فَمَن كَانَ مِنكُم مَّرِيضًا أَوْ عَلَىٰ سَفَرٍ فَعِدَّةٌ مِّنْ أَيَّامٍ أُخَرَ ۚ وَعَلَى الَّذِينَ يُطِيقُونَهُ فِدْيَةٌ طَعَامُ مِسْكِينٍ ۖ فَمَن تَطَوَّعَ خَيْرًا فَهُوَ خَيْرٌ لَّهُ ۚ وَأَن تَصُومُوا خَيْرٌ لَّكُمْ ۖ إِن كُنتُمْ تَعْلَمُونَ
Fasting) for a fixed number of days; but if any of you is ill, or on a journey, the prescribed number (Should be made up) from days later. For those who can do it (With hardship), is a ransom, the feeding of one that is indigent. But he that will give more, of his own free will,- it is better for him. And it is better for you that ye fast, if ye only knew.
شَهْرُ رَمَضَانَ الَّذِي أُنزِلَ فِيهِ الْقُرْآنُ هُدًى لِّلنَّاسِ وَبَيِّنَاتٍ مِّنَ الْهُدَىٰ وَالْفُرْقَانِ ۚ فَمَن شَهِدَ مِنكُمُ الشَّهْرَ فَلْيَصُمْهُ ۖ وَمَن كَانَ مَرِيضًا أَوْ عَلَىٰ سَفَرٍ فَعِدَّةٌ مِّنْ أَيَّامٍ أُخَرَ ۗ يُرِيدُ اللَّهُ بِكُمُ الْيُسْرَ وَلَا يُرِيدُ بِكُمُ الْعُسْرَ وَلِتُكْمِلُوا الْعِدَّةَ وَلِتُكَبِّرُوا اللَّهَ عَلَىٰ مَا هَدَاكُمْ وَلَعَلَّكُمْ تَشْكُرُونَ
Ramadhan is the (month) in which was sent down the Qur´an, as a guide to mankind, also clear (Signs) for guidance and judgment (Between right and wrong). So every one of you who is present (at his home) during that month should spend it in fasting, but if any one is ill, or on a journey, the prescribed period (Should be made up) by days later. Allah intends every facility for you; He does not want to put to difficulties. (He wants you) to complete the prescribed period, and to glorify Him in that He has guided you; and perchance ye shall be grateful.
أُحِلَّ لَكُمْ لَيْلَةَ الصِّيَامِ الرَّفَثُ إِلَىٰ نِسَائِكُمْ ۚ هُنَّ لِبَاسٌ لَّكُمْ وَأَنتُمْ لِبَاسٌ لَّهُنَّ ۗ عَلِمَ اللَّهُ أَنَّكُمْ كُنتُمْ تَخْتَانُونَ أَنفُسَكُمْ فَتَابَ عَلَيْكُمْ وَعَفَا عَنكُمْ ۖ فَالْآنَ بَاشِرُوهُنَّ وَابْتَغُوا مَا كَتَبَ اللَّهُ لَكُمْ ۚ وَكُلُوا وَاشْرَبُوا حَتَّىٰ يَتَبَيَّنَ لَكُمُ الْخَيْطُ الْأَبْيَضُ مِنَ الْخَيْطِ الْأَسْوَدِ مِنَ الْفَجْرِ ۖ ثُمَّ أَتِمُّوا الصِّيَامَ إِلَى اللَّيْلِ ۚ وَلَا تُبَاشِرُوهُنَّ وَأَنتُمْ عَاكِفُونَ فِي الْمَسَاجِدِ ۗ تِلْكَ حُدُودُ اللَّهِ فَلَا تَقْرَبُوهَا ۗ كَذَٰلِكَ يُبَيِّنُ اللَّهُ آيَاتِهِ لِلنَّاسِ لَعَلَّهُمْ يَتَّقُونَ
Permitted to you, on the night of the fasts, is the approach to your wives. They are your garments and ye are their garments. Allah knoweth what ye used to do secretly among yourselves; but He turned to you and forgave you; so now associate with them, and seek what Allah Hath ordained for you, and eat and drink, until the white thread of dawn appear to you distinct from its black thread; then complete your fast Till the night appears; but do not associate with your wives while ye are in retreat in the mosques. Those are Limits (set by) Allah: Approach not nigh thereto. Thus doth Allah make clear His Signs to men: that they may learn self-restraint.
وَأَتِمُّوا الْحَجَّ وَالْعُمْرَةَ لِلَّهِ ۚ فَإِنْ أُحْصِرْتُمْ فَمَا اسْتَيْسَرَ مِنَ الْهَدْيِ ۖ وَلَا تَحْلِقُوا رُءُوسَكُمْ حَتَّىٰ يَبْلُغَ الْهَدْيُ مَحِلَّهُ ۚ فَمَن كَانَ مِنكُم مَّرِيضًا أَوْ بِهِ أَذًى مِّن رَّأْسِهِ فَفِدْيَةٌ مِّن صِيَامٍ أَوْ صَدَقَةٍ أَوْ نُسُكٍ ۚ فَإِذَا أَمِنتُمْ فَمَن تَمَتَّعَ بِالْعُمْرَةِ إِلَى الْحَجِّ فَمَا اسْتَيْسَرَ مِنَ الْهَدْيِ ۚ فَمَن لَّمْ يَجِدْ فَصِيَامُ ثَلَاثَةِ أَيَّامٍ فِي الْحَجِّ وَسَبْعَةٍ إِذَا رَجَعْتُمْ ۗ تِلْكَ عَشَرَةٌ كَامِلَةٌ ۗ ذَٰلِكَ لِمَن لَّمْ يَكُنْ أَهْلُهُ حَاضِرِي الْمَسْجِدِ الْحَرَامِ ۚ وَاتَّقُوا اللَّهَ وَاعْلَمُوا أَنَّ اللَّهَ شَدِيدُ الْعِقَابِ
And complete the Hajj or ´umra in the service of Allah. But if ye are prevented (From completing it), send an offering for sacrifice, such as ye may find, and do not shave your heads until the offering reaches the place of sacrifice. And if any of you is ill, or has an ailment in his scalp, (Necessitating shaving), (He should) in compensation either fast, or feed the poor, or offer sacrifice; and when ye are in peaceful conditions (again), if any one wishes to continue the ´umra on to the hajj, He must make an offering, such as he can afford, but if he cannot afford it, He should fast three days during the hajj and seven days on his return, Making ten days in all. This is for those whose household is not in (the precincts of) the Sacred Mosque. And fear Allah, and know that Allah Is strict in punishment.
كَانَ النَّاسُ أُمَّةً وَاحِدَةً فَبَعَثَ اللَّهُ النَّبِيِّينَ مُبَشِّرِينَ وَمُنذِرِينَ وَأَنزَلَ مَعَهُمُ الْكِتَابَ بِالْحَقِّ لِيَحْكُمَ بَيْنَ النَّاسِ فِيمَا اخْتَلَفُوا فِيهِ ۚ وَمَا اخْتَلَفَ فِيهِ إِلَّا الَّذِينَ أُوتُوهُ مِن بَعْدِ مَا جَاءَتْهُمُ الْبَيِّنَاتُ بَغْيًا بَيْنَهُمْ ۖ فَهَدَى اللَّهُ الَّذِينَ آمَنُوا لِمَا اخْتَلَفُوا فِيهِ مِنَ الْحَقِّ بِإِذْنِهِ ۗ وَاللَّهُ يَهْدِي مَن يَشَاءُ إِلَىٰ صِرَاطٍ مُّسْتَقِيمٍ
Mankind was one single nation, and Allah sent Messengers with glad tidings and warnings; and with them He sent the Book in truth, to judge between people in matters wherein they differed; but the People of the Book, after the clear Signs came to them, did not differ among themselves, except through selfish contumacy. Allah by His Grace Guided the believers to the Truth, concerning that wherein they differed. For Allah guided whom He will to a path that is straight.
أَمْ حَسِبْتُمْ أَن تَدْخُلُوا الْجَنَّةَ وَلَمَّا يَأْتِكُم مَّثَلُ الَّذِينَ خَلَوْا مِن قَبْلِكُم ۖ مَّسَّتْهُمُ الْبَأْسَاءُ وَالضَّرَّاءُ وَزُلْزِلُوا حَتَّىٰ يَقُولَ الرَّسُولُ وَالَّذِينَ آمَنُوا مَعَهُ مَتَىٰ نَصْرُ اللَّهِ ۗ أَلَا إِنَّ نَصْرَ اللَّهِ قَرِيبٌ
Or do ye think that ye shall enter the Garden (of bliss) without such (trials) as came to those who passed away before you? they encountered suffering and adversity, and were so shaken in spirit that even the Messenger and those of faith who were with him cried: "When (will come) the help of Allah?" Ah! Verily, the help of Allah is (always) near.