Sayyiduna Imran bin Husayn (may Allah be pleased with him) said: "The Messenger of Allah (peace and blessings be upon him) had one pause." Sayyiduna Samurah (may Allah be pleased with him) said: "There were two pauses." So they wrote to Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him), and he wrote back: You have remembered correctly, O Samurah, and the people have forgotten.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15402