Recommended times for supplication
Chapter on the Prayer for Rain (Istisqa)
Al-Mughni
Book of the Eclipse Prayers (Solar and Lunar)
Primary text
It is recommended to make supplication when rain descends. This is based on the report that the Prophet, peace be upon him, said: Seek the acceptance of supplication at three times: at the meeting of armies, at the establishment of prayer, and at the descent of rain.