Sunan at-Tirmidhi (Jami-al-Tirmidhi), Chapter: Salah (Prayers)

from Qatadab who from Hasan that Sayyidina Samurah (RA) narrated having rememberred two silent periods in salah. Sayyidina breran ibn Husayn Denied that, saying, 'We remember only one period of silence." So, they wrote to Sayyidina Ubayy ibn Ka'b at Madinah and he wrote back that Samurah rememberred correctly. Sa'eed said that they asked Qatadah what those periods of silence were. He said, "(They were) When one begins the salah (after the first takbir) and when one finishes the recital at Waladdaaleen . The narrator said that he liked very much the silence on finishing the recital till he had regained his breath. [Abu Dawud 780, Ibn e Majah 844]