It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When you come to the prayer and we are in prostration, then join in the prostration too, and do not count it as anything; and whoever catches one rak'ah has, as it were, caught the (whole) prayer."
Only Yahya bin Abi Sulayman al-Madini narrated it, and it has been narrated from Abu Hurayrah through another chain that is weaker than this one.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2574