مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2491
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Muhammad that Ibn 'Abbas - Ibn ‘Awn said: I think he attributed it to the Prophet (ﷺ) - instructed a caller to call out on a rainy day: “Pray where you are (where your mounts or tents are).”
Musnad Ahmad 2503Its isnad is saheeh, al-Bukhari (616) and Muslim (699)]