Ibn Abi Layla (may Allah have mercy on him) says: Our companions narrated to us that when a man came to pray, he would be told how much of the prayer had passed, and they would be with the Prophet (peace and blessings be upon him) standing, bowing, sitting and praying. Sayyiduna Mu'adh (may Allah be pleased with him) came, and they pointed it out to him. Shu'bah says: I heard this from Husayn, from Ibn Abi Layla, that Sayyiduna Mu'adh (may Allah be pleased with him) said: In whatever state I see the Prophet (peace and blessings be upon him), I will join the prayer in that same state. He (peace and blessings be upon him) said: "Mu'adh (may Allah be pleased with him) has established a way for you; you should do likewise."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5147