Asim bin Damrah (may Allah have mercy on him) said: Some people came to Sayyiduna Ali (may Allah be pleased with him) and asked about witr. Sayyiduna Ali (may Allah be pleased with him) said: Have you asked anyone else about it as well? They said: We asked Sayyiduna Abu Musa (may Allah be pleased with him), and he said: There is no witr after the adhan. Sayyiduna Ali (may Allah be pleased with him) said: He has gone to an extreme and overstepped the bounds in giving the fatwa. The time of witr is between Isha and the morning prayer; whenever you pray witr, it is good.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4526