It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) led them in the Fajr prayer while it was still night (before its time), then he led it again, and this happened three times.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2153