In a Muslim prayer, the Prophet Muhammad, Sallallahu ‘Alaihi Wasallam, raised both his hands while standing i’tidal (after ruku’) in the way as is done on takbiratul ihram.
As noted in the following hadiths:
1. Abu Hurairah, Radhiyallahu Anhu, reported that Allah’s Messenger, Sallallahu ‘Alaihi Wasallam, said: When the imam says:
سَمِعَ اللهُ لِمَنْ حَمِدَهُ
Sami’allaahu liman hamidah
Allah listened to one who praised Him,
Those following in prayer should say:
اللَّهُـمَّ رَبَّنَا لَكَ الْحَمْدُ
Allahumma robbanaa lakal hamd
O Allah, our Lord, to You is the praise due
This is according to the hadith that says: as he whose words coincide with the words of the angels, his previous sins are pardoned. (Bukhari : 796, Muslim: 476)
2. Rifea bin Rafi, Radhiyallahu Anhu, reported: We used to observe prayer behind Allah’s Apostle, Sallallahu ‘Alaihi Wasallam, and as he raised his head from ruku’, he said:
سَمِعَ اللهُ لِمَنْ حَمِدَهُ
Sami’allaahu liman hamidah
Allah listened to one who praised Him
And a person behind him said:
رَبَّنَا وَلَكَ الْحَمْدُ، حَمْدًا كَثِيْرًا طَيِّبًا مُبَارَكًا فِيْهِ
Robbanaa wa lakal hamdu hamdan katsiiron thoyyiban mubaarokan fiih
Our Lord, to You is the praise due, the praise in abundance, pure and blessed
Allah’s Messenger, Sallallahu ‘Alaihi Wasallam, concluded his prayer and he said: Who has just recited? (The person said): It is me. Whereupon he said: I saw more than thirty angels trying to vie with one another as to who should first record it (Bukhari: 799).
3. Abdullah bin Abi Aufa, Radhiyallahu Anhu, reported that when Allah’s Messenger, Sallallahu ‘Alaihi Wasallam, raised up his back from bowing, he used to say:
Sami’allaahu liman hamidah Allaahumma robbanaa lakal hamdu mil assamaawaati wa mil al ardhi wa mil a maa shi’ta min shaiim ba’du
Allah listened to one who praised Him, O Allah, our Lord, to You is all the praise, filling the heavens and the earth and filling whatever You wish besides them. (Muslim: 476)
4. Abu Sa’id Al Khudri, Radhiyallahu Anhu, reported that when Allah’s Messenger, Sallallahu ‘Alaihi Wasallam, raised up his head from ruku, he used to say:
رَبَّنَا لَكَ الْحَمْدُ
مِلْءَ السَّمَاوَاتِ وَمِلْءَ اْلأَرْضِ وَمِلْءَ مَا شِئْتَ مِنْ شَيْءٍ بَعْدُ. أَهْلَ الثَّنَاءِ وَالْمَجْدِ، أَحَقُّ مَا قَالَ الْعَبْدُ، وَكُلُّنَا لَكَ عَبْدٌ. اَللَّهُمَّ لاَ مَانِعَ لِمَا أَعْطَيْتَ، وَلاَ مُعْطِيَ لِمَا مَنَعْتَ، وَلاَ يَنْفَعُ ذَا الْجَدِّ مِنْكَ الْجَدُّ
Robbanaa lakal hamdu mil assamaawaati wa mil al ardhi wa mil a maa shi’ta min shai in ba’du ahlutstsanaa i walmajdi a haqqu maa qoolal ‘abdu wa kullunaa laka ‘abdan, Allaahumma laa maa ni’a limaa a’toyta wa laa mu’tiya limaa mana’ta wa laa yanfa’u dhaal jaddi minkal jaddu
O Allah, our Lord to You is the praise due, filling heavens and filling earth and filling what You wish besides them, You are worthy of praise and glory, most worthy of what a slave says, and everyone of us is your slave. O Allah, there is none to withold what You give and there is none to give what You withhold. Wealth gives no benefit to a wealthy man against Your will. (Muslim: 477)
Reference: The Prayer of Muhammad, Sallallahu ‘Alaihi Wasallam, by Syed Shafiq Ur-Rahman