Sahih Ibn Khuzaymah

Hazrat Salim (may Allah have mercy on him) narrates from his respected father, Sayyiduna Abdullah (may Allah be pleased with him), who says: I saw the Messenger of Allah (peace and blessings be upon him) raising his hands to the level of his shoulders when he began the prayer, when he intended to bow (ruku‘), and after raising his head from bowing. And the Prophet (peace and blessings be upon him) did not raise his hands between the two prostrations. These are the words of Ibn Rafi‘’s narration. I heard Makhzumi saying: Which chain can be more authentic than this chain? Imam Sufyan Thawri (may Allah have mercy on him) said: This chain is as strong and firm as this pillar.

Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) narrates from the Noble Prophet (peace and blessings be upon him) that when the Prophet (peace and blessings be upon him) would stand for the obligatory prayer, he would say « اللهُ أَكْبَرُ » and raise both his hands up to his shoulders. When he completed his recitation and intended to bow (ruku‘), he would also perform the raising of the hands in the same manner, and when he raised his head from ruku‘, he would again raise his hands in the same way. And the Prophet (peace and blessings be upon him) would not raise his hands while sitting in his prayer. And when he stood up after the tashahhud of two rak‘ahs, he would raise his hands in the same way and say « اللهُ أَكْبَرُ ».