The ihram and the talbiya - Section 2 Mishkat al-Masabih 2547
Arabic hadith text
عَنْ زَيْدِ بْنِ ثَابِتٍ أَنَّهُ رَأَى النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ تَجَرَّدَ لِإِهْلَالِهِ وَاغْتَسَلَ. رَوَاهُ التِّرْمِذِيّ والدارمي
Translation
Zaid b. Thabit said he saw the Prophet strip to put on his ihram, and bathe. Tirmidhi and Darimi transmitted it.