Musannaf Ibn Abi Shaybah 4042 — A man supporting himself on his hands

Sayyiduna Ali (may Allah be pleased with him) said: "The Sunnah in an obligatory prayer is that a man should not support himself with his hands on the ground when rising in the first two rak'ahs, unless he is an old man who does not have the strength to rise without support; then it is permitted for him."