It is narrated from Ibn Umar (may Allah be pleased with him) that he stated: When the night was cold and windy, the Prophet ﷺ would instruct the muezzin to say in the adhan: "Ala sallu fi r-rihal" (Be aware! Pray in your homes!).
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 276
Hadith Takhrijاخرجہ البخاری: الاذان، باب الرخصة فی المطر والعلة ان یصلی فی رحلہ: 666، ومسلم، الصلاة، باب الصلاة فی الرحال فی المطر: 697۔