It is narrated from Nafi' (may Allah have mercy on him) that Ibn Umar (may Allah be pleased with him) once gave the call to prayer on a cold and windy night and said: " ألا صلوا فى الرحال (Pray in your dwellings)." Then he said: When the night was cold and rainy, the Messenger of Allah (peace and blessings be upon him) would order the mu'adhdhin to say in the call to prayer: " ألا صلوا فى الرحال (Pray in your dwellings)."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 277
Hadith Takhrijاخرجہ البخاری: الاذان، باب الرخصة فی المطر والعلة ان یصلی فی رحلہ: 666، ومسلم، الصلاة، باب الصلاة فی الرحال فی المطر: 697۔