He saw that when the Prophet ﷺ began the prayer, he would raise his hands until his thumbs were nearly level with his earlobes.
أخبرنا محمد بن رافع قال حدثنا محمد بن بشر قال حدثنا فطر بن خليفة
أنه رأى النبي ﷺ إذا افتتح الصلاة رفع يديه حتى تكاد إبهاماه تحاذي شحمة أذنيه
[Its chain is daif]. Abu Dawud recorded it in the Book of Prayer, chapter on the opening of prayer, hadith no. 737, through the narration of Fitr, and it is also in Sunan al-Kubra, no. 956. Nasai said in Sunan al-Kubra, "Abdul-Jabbar bin Waail did not hear from his father, though the hadith itself is sahih."