Sayyiduna Abu Salamah (may Allah be pleased with him) said: I saw Sayyiduna Abu Hurairah (may Allah be pleased with him) prostrating in «إِذَاالسَّمَاءُانْشَقَّتْ»[سورة الانشقاق 1/84], so I asked: O Abu Hurairah! What is this, I see you prostrating in «إِذَاالسَّمَاءُانْشَقَّتْ»? He replied: If I had not seen the Messenger of Allah (peace and blessings be upon him) prostrating in it, I would never have prostrated either.
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1508