Answered by Tabraze Azam
Answer: Assalamu alaikum wa rahmatullahi wa barakatuh
It would be improper to pray in one’s pajamas, when reasonably avoidable. [Ibn `Abidin, Radd al-Muhtar]
The Messenger of Allah (Allah bless him and give him peace) said, “Allah is more deserving of one’s modesty than people are.” [Tirmidhi; Abu Dawud] Therefore, one would ideally wear dignified clothing as per the Prophetic example, keeping in mind the majesty of the One you are addressing. This would be the sunna.
However, it one is tired or has another reasonable excuse, it would be permitted without dislike to pray in one’s pajamas.
Wassalam,
Tabraze Azam
Checked & Approved by Faraz Rabbani