Hadith: Allah Almighty said: 'I have divided prayer between Myself and My servant into two halves, and My servant shall have what he has asked for

عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللهُ عنه سَمِعْتُ رَسُولَ اللهِ صلى الله عليه وسلم يَقُولُ:
«قَالَ اللهُ تَعَالَى: قَسَمْتُ الصَّلَاةَ بَيْنِي وَبَيْنَ عَبْدِي نِصْفَيْنِ، وَلِعَبْدِي مَا سَأَلَ، فَإِذَا قَالَ الْعَبْدُ: {الْحَمْدُ لِلهِ رَبِّ الْعَالَمِينَ}، قَالَ اللهُ تَعَالَى: حَمِدَنِي عَبْدِي، وَإِذَا قَالَ: {الرَّحْمَنِ الرَّحِيمِ}، قَالَ اللهُ تَعَالَى: أَثْنَى عَلَيَّ عَبْدِي، وَإِذَا قَالَ: {مَالِكِ يَوْمِ الدِّينِ}، قَالَ: مَجَّدَنِي عَبْدِي، -وَقَالَ مَرَّةً: فَوَّضَ إِلَيَّ عَبْدِي-، فَإِذَا قَالَ: {إِيَّاكَ نَعْبُدُ وَإِيَّاكَ نَسْتَعِينُ}، قَالَ: هَذَا بَيْنِي وَبَيْنَ عَبْدِي وَلِعَبْدِي مَا سَأَلَ، فَإِذَا قَالَ: {اهْدِنَا الصِّرَاطَ الْمُسْتَقِيمَ، صِرَاطَ الَّذِينَ أَنْعَمْتَ عَلَيْهِمْ غَيْرِ الْمَغْضُوبِ عَلَيْهِمْ وَلا الضَّالِّينَ}، قَالَ: هَذَا لِعَبْدِي وَلِعَبْدِي مَا سَأَلَ».
[صحيح] - [رواه مسلم] - [صحيح مسلم: 395]

Abu Hurayrah (may Allah be pleased with him) reported: I heard the Messenger of Allah (may Allah's peace and blessings be upon him) say:
"Allah Almighty said: 'I have divided prayer between Myself and My servant into two halves, and My servant shall have what he has asked for.' When the servant says, '{All praise be to Allah, the Lord of the worlds}', Allah Almighty says: 'My servant has praised Me.' And when he says, '{The Most Compassionate, the Most Merciful}', Allah Almighty says: 'My servant has extolled Me.' And when he says, '{Master of the Day of Judgment}', Allah Almighty says: 'My servant has glorified Me' - And He also says: 'My servant entrusted his affairs to Me' - And when he says, '{You alone we worship, and You alone we ask for help}', He says: 'This is between Me and My servant, and My servant shall have what he has asked for.' And when he says, '{Guide us to the straight path, the path of those whom You have blessed; not of those who incurred Your Wrath, or of those who went astray}', He says: 'This is for My servant, and My servant shall have what he has asked for.'"
[Authentic hadith] - [Narrated by Muslim] - [Sahih Muslim - 395]

Explanation

The Prophet (may Allah's peace and blessings be upon him) informed that Allah Almighty, in a Qudsi Hadīth, said: I have divided Surat al-Fātihah in prayer between Myself and My servant in two halves; a half for Myself and a half for him.
In the first half: praise, exaltation, and glorification of Allah, for which I give him the best reward.
And in the second half: entreaty and supplication, to which I respond and give him what he has asked for.
When the praying person says, {All praise be to Allah, the Lord of the worlds}, Allah says: My servant has praised Me. And when he says, {The Most Compassionate, the Most Merciful}, Allah says: My servant has extolled Me, praised Me, and acknowledged My general favor upon My servants. And when he says, {Master of the Day of Judgment}, Allah says: My servant has glorified Me - and that is a great honor.
And when he says, {You alone we worship, and You alone we ask for help}', Allah says: This is between Me and My servant.
The first part of this verse, namely {You alone we worship), is an acknowledgment of the divinity of Allah and responding to Him with worship, and with it the half which is for Allah comes to an end.
The second part of the verse, namely {and You alone we ask for help}, contains the quest for help from Allah and His promise of help.
And when he says, {Guide us to the straight path*, the path of those whom You have blessed; not of those who incurred Your Wrath, or of those who went astray}, Allah says: This is entreaty and supplication from My servant, and My servant shall have what he has asked for, and I have answered his supplication.