Answered by Shaykh Faraz Rabbani
I understand that a latecomer for a ‘silent’ prayer must say the thana (subhanakallahuma wa…wa la ilaha ghairuk) if they catch the Imam standing. However, must they also say ‘awoosubillahi minishaytan ir rajeem’ at anytime during the salat, such as during the first rakat they make up?
Walaikum assalam wa rahmatullah,
1. The follower doesn’t recite the ta`awwudh (saying “A`udhu billahi min’ash shaytan’ir rajeem”), because this is a sunna of recitation and the follower doesn’t recite behind the imam. However, if they are a latecomer (i.e. having missed one or more rakats), then they say it when they begin making up the missed rakats of prayer. (Haskafi, Durr)
2. As for the opening supplication (thana’):
(a) If one catches the imam in a quiet prayer, one says the opening supplication (thana’).
(b) If in a loud prayer and the imam has begun reciting, one doesn’t say it then. (Ibn Abidin, Radd al-Muhtar)
And Allah alone gives success.
Faraz Rabbani