Abu Uthman said that Sayyiduna Abu Bakr and Umar (may Allah be pleased with them both) used to recite the qunut in the morning prayer after the bowing.
Yahya bin Sa'id al-Qattan narrated this same hadith to us via al-Awwam bin Hamzah, and in it he also mentioned the name of Sayyiduna Uthman bin Affan (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3132