It is narrated from Wa'il bin Hujr (may Allah be pleased with him) that when the Prophet (peace and blessings be upon him) prostrated, his knees would rest on the ground before his hands, and when he rose, he would raise his hands before his knees.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2628
(a) Abd al-Jabbar narrates from his father Wa'il bin Hujr (may Allah be pleased with him) that when he (peace and blessings be upon him) began the prayer, he raised his hands and said 'Allahu akbar', then he wrapped his hands in his garment and placed the right hand over the left. When he intended to bow, he did like this; then he brought his hands out of the garment, then raised his hands and said the takbir. Then, when he (peace and blessings be upon him) intended to prostrate, his knees would already have touched the ground before his hands. When he prostrated, his forehead was between his two hands, and he (peace and blessings be upon him) kept his arms well away from his armpits.
(b) Hammam said: Then, when he rose, he rose on his knees and supported himself on his thighs.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2629
Asim bin Kulayb (may Allah have mercy on him) narrates from his father (may Allah have mercy on him) that when the Prophet (peace and blessings be upon him) prostrated, his knees would already have rested on the ground before his hands.
Affan said: This hadith is gharib (strange). This hadith is counted among the solitary reports of Sharik al-Qadi; Hammam corroborated him through this route only as mursal (without the Companion). This is how al-Bukhari and other early hadith masters (may Allah have mercy on them) mentioned it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2630
It is narrated from Sayyiduna Wa'il bin Hujr (may Allah be pleased with him): I prayed behind the Messenger of Allah (peace and blessings be upon him); then he (peace and blessings be upon him) prostrated, and when going down into prostration the first part of him (peace and blessings be upon him) to touch the ground was his knees.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2631
(a) It is narrated from Sayyiduna Anas (may Allah be pleased with him): I saw the Messenger of Allah (peace and blessings be upon him) say the takbir, and he raised his two thumbs up to his ears; then he bowed until every joint settled in its place; then he raised his head from bowing until every joint was straight in its place; then he went down into prostration saying the takbir, until his knees touched the ground before his hands.
(b) An account of placing the knees before the hands, from the practice of Sayyiduna Umar bin al-Khattab and Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with them both).
Al-Ala' bin Isma'il is alone in narrating it, and Allah Almighty knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2632