Sayyiduna Anas (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) entered ihram after the prayer.
Al-Bazzar recorded it, and its narrators are the narrators of the Sahih, except for al-Bazzar's teacher, whose case is different; al-Tirmidhi declared his hadith hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحج / 5354