Nafi' narrates from Ibn Umar (may Allah be pleased with them both) that when he gave the call to prayer on a cold, rainy and windy night, he would say at the end of the adhan: 'Ala sallu fi al-rihal' "Pray in your dwellings." Then he would say: The Messenger of Allah (peace and blessings be upon him) used to order the caller to prayer, when the night was cold or rainy on a journey, to say: "'Ala sallu fi rihalikum', pray in your dwellings."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5019