Musannaf Ibn Abi Shayba 3:811

Yazid ibn Harun narrated to us, he said: Dawud ibn Abi Hind informed us, from Abu Nadra, from Abu Sa'id al-Khudri, who said: Ubayy ibn Ka'b and Ibn Mas'ud differed regarding prayer in a single garment. Ubayy said: "A [single] garment," and Ibn Mas'ud said: "Two garments." Umar came out to them and blamed them, and said: "It displeases me that two of the companions of Muhammad differ regarding the same thing. So upon which of your two legal opinions will the people act? As for Ibn Mas'ud, he did not fall short, but the correct view is what Ubayy said."