Sayyiduna Samurah bin Jundub (may Allah be pleased with him) said: the Messenger of Allah (peace and blessings be upon him) used to observe two pauses (saktah): when he entered into the prayer, and when he finished the recitation. Sayyiduna Imran bin Husayn (may Allah be pleased with him) objected to that, so the people wrote about it to Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him), and he wrote back to them: Samurah has spoken the truth.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6912