Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.129A.
Section : Sunnah acts of prayer, Raising the Hands.
This must be done at the beginning of each prayer’s takbir. Says Ibn al-Munzhir, “All scholars agree that the Prophet raised his hands at the beginning of his prayer.”
Commenting upon this report, Ibn Hajr says, “The Prophet’s raising his hands at the beginning of his prayer has been narrated by fifty companions, including the ten who were given the tidings of Paradise. ” Al-Baihaqi related that al-Hakim said, “I do not know of any sunnah other than this one which is accepted by the four rightly-guided khalifahs, the ten companions who were given the tidings of Paradise, and other companions scattered across many lands.” Summing up his evaluation of the report, al-Baihaqi says, “And it is as our teacher Abu ‘Abdullah has said.”