It is narrated from Sayyiduna Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) would perform Witr near the time of the Fajr adhan, and would offer the Sunnah of Fajr near the time of the iqamah.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 659
Hadith Gradingحکم دارالسلام:إسناده ضعيف، شريك وهو ابن عبدالله القاضي، سيء الحفظ، والحارث وهو ابن عبدالله الأعور ضعيف