The Messenger of Allah ﷺ said, "When you come to the prayer and we are in prostration, then prostrate, but do not count it as anything. Whoever catches the bowing has caught the unit of prayer."
حدثنا محمد بن يحيى بن فارس أن سعيد بن الحكم حدثهم أخبرنا نافع بن يزيد حدثني يحيى بن أبي سليمان عن زيد بن أبي العتاب وابن المقبري
قال رسول الله ﷺ إذا جئتم إلى الصلاة ونحن سجود فاسجدوا ولا تعدوها شيئا ومن أدرك الركعة فقد أدرك الصلاة
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[Its chain is daif] Ibn Khuzayma narrated it, no. 1622, from the hadith of Saeed bin Hakam through the same route. Hakim graded it sahih at 1/216, 273, 274, and Dhahabi agreed with him.Ibn Khuzayma, may Allah have mercy on him, criticized it and did not grade it sahih. Yahya bin Abu Sulayman was graded daif by Bukhari and the majority. The hadith has daif corroborating narrations.