It is a segment of a lengthy hadith reported by al-Tabarani in al-Muʿjam al-Saghir (p. 177). Abu Yaʿla al-Mawsili also related it—the citation appears in al-Laali al-Masnuʿa (2/203) and Nasb al-Rayah (1/372–373)—through the chain of ʿAli b. Zayd b. Judʿan from Saʿid b. al-Musayyab, from him. The isnad is hasan and suitable for corroboration. Al-Tirmidhi transmitted part of the hadith as well (2/113, 117, Bulaq ed.) through this same route and remarked: “The report contains a long story. From this route it is hasan and gharib. ʿAli b. Zayd is reliable, though he sometimes ascribes to the Prophet what others halt at a Companion.” There is another supporting narration, marfuʿ, from Ibn ʿAbbas: “When you bow, place your palms on your knees until you are steady; when you prostrate, press your forehead firmly to the ground until you feel the ground’s pressure.” Ahmad recorded it (1/287) through Salih, the freedman of al-Tuʿama, from him, but the isnad is weak. (1) This version comes from the Companion Abu Masʿud ʿUqbah b. ʿAmr al-Badri. ʿAtaʾ b. al-Saʾib narrated from Salim al-Barrad, who said: “We went to ʿUqbah b. ʿAmr al-Ansari—Abu Masʿud—and said, ‘Tell us about the prayer of the Messenger of Allah.’ He stood before us in the mosque and pronounced the takbir; when he bowed, he placed his hands on his knees, put his fingers below them, and kept his elbows away from his sides until every limb was at rest. Then he said, ‘Allah hears the one who praises Him,’ and stood until everything had settled. Next he pronounced the takbir, prostrated, set his palms on the ground, and again distanced his elbows until all was still. He then raised his head, sat until he was composed, repeated the same actions, and finally prayed four rakʿahs in this manner.”