Imam Ibn Sirin (may Allah have mercy on him) says that I asked Hazrat Anas (may Allah be pleased with him) whether Hazrat Umar (may Allah be pleased with him) used to recite Qunoot Nazilah. He replied that a person better than Hazrat Umar (may Allah be pleased with him), that is, the Prophet (peace and blessings be upon him), also used to recite Qunoot Nazilah after bowing (ruku).
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 12698
Hadith Gradingحکم دارالسلام:إسناده ضعيف لضعف محبوب بن الحسن