From Sahih Muslim (Hadith 3044):
Ibn Umar (Allah be pleased with him) reported that Allah's Messenger may peace be upon him) spent the night at Dhi Tuwa till it was dawn and then entered Mecca. 'Abdullah (b. 'Umar) himself did like it. And in the narration transmitted by Ibn Sa'ld (the words are):Until he obrerved the dawn prayer. Yahya (another narrator) said: Until it was dawn
Reference: Muslim 3044