Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.129B.
Section : Sunnah acts of prayer, How to Raise the Hands.
Many narrations have been recorded concerning this subject. Many scholars have chosen the following forms: the hands are raised to the shoulders with the fingertips parallel to the button of the ears. Says an-Nawawi, “This is how ash-Shaifi combined the hadith (on this question), and the people found it to be good.” It is preferred that one extends the fingers while raising the hands. Abu Hurairah said, “When the Prophet, upon whom be peace, stood for prayer, he would raise his hands (with them being) open.” (Related by “the five,” except for Ibn Majah.)