Ibn Umar used to place his hands down before his knees, and he said, "The Messenger of Allah ﷺ used to do that."
عن ابن عمر أنه كان يضع يديه قبل ركبتيه، وقال: كان رسول الله ﷺ يفعل ذلك.
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Ibn Khuzayma (627), Daraqutni (1303), Hakim (1/226) and from him Bayhaqi (2/100), and Tahawi in his Sharh (2541), all narrated it through routes going back to Abdul-Aziz bin Muhammad Darawardi, from Ubaydullah bin Umar, from Nafi, from Ibn Umar, and he mentioned it. Its chain is sahih. Hakim said, "Sahih according to the criterion of Muslim." He also said, "As for where my heart leans on this matter, it inclines toward the hadith of Ibn Umar, because of the many narrations on this subject from the companions and the successors." End of quote.Bukhari cited it with a dropped chain in his Sahih (2/290), and Hafiz attributed it to those to whom I have attributed it.However, something contrary to this has been narrated from Ibn Umar. Ibn Abu Layla narrated from Nafi, from Ibn Umar, that he used to place his knees down before his hands when he prostrated, and would raise his hands before his knees when he rose. Ibn Abu Shayba recorded it (1/263) from Yaqub bin Ibrahim, from Ibn Abu Layla, from Nafi, from Ibn Umar. However, its chain is daif because of Ibn Abu Layla, who had poor memory.As for what has come from Ibn Umar, both as his own statement and as one attributed to the Prophet, that he said, "When one of you prostrates, let him place his knees down, and when he rises, let him raise them, for the hands prostrate just as the face prostrates," its sourcing will come later. This indicates that the sajdah involves placing the hands on the ground just as the face is placed upon it. This does not contradict the narration attributed to the Prophet, as Bayhaqi understood it, for he said, right after citing the hadith of Darawardi,"What is well known from Abdullah bin Umar on this matter is what Abu Hasan Ali bin Muhammad Muqri told us, who said Hasan bin Muhammad bin Ishaq told us, who said Yusuf bin Yaqub Qadi told us, who said Sulayman bin Harb told us, who said Hammad bin Zayd told us, from Ayub, from Nafi, from Ibn Umar, who said (and he mentioned it)." Then he narrated it through the route of Ismail bin Ulaya, from Ayub with his chain, and as a narration attributed to the Prophet, saying, "The hands prostrate just as the face prostrates. So when one of you places his face down, let him place his hands down, and when he raises it, let him raise them." Ahmad bin Sinan likewise narrated it from Ismail. "What is meant by it is the placing of the hands during the sujud, not which of them comes first." End of quote.It is as if he is saying that the narration attributed to the Prophet which Darawardi narrated is meant to convey this same point, not the precedence of placing the hands in the sujud. But what is apparent from the two contexts is that they differ.