Is the congregational supplication following the prescribed prayers, with the wording: "O Allah, water Your servants and Your beasts, spread Your mercy, and revive Your dead land. O Allah, grant us relief! O Allah, grant us relief! And do not make us among the despairing," legislated?

It is permissible to make supplications for rain after prayers, and this is one of the legitimate forms of seeking rain (Istisqa') according to the majority of jurists. Imam Malik held that it is permissible to seek rain after the Maghrib and Fajr prayers, and Ibn Rushd restricted it to supplication, not going out to the prayer ground. Imam Shafi'i permitted the Imam to seek rain without prayer, or after it, or after his sermon and prayer. Ibn Qudamah mentioned that seeking rain has three forms: the most complete is going out and praying, followed by the Imam seeking rain on the minbar on Friday, and the third is supplication after prayers and in private. Shaykh al-Islam Ibn Taymiyyah said that seeking rain can be done in three ways: supplication after prayers, or going out to the prayer ground for supplication without prayer, or prayer and supplication. The first two ways are legitimate by the consensus of the Ummah, and the third is legitimate according to the majority. As for Abu Hanifa, he said: "There is no prescribed communal prayer for seeking rain. If people pray individually, it is permissible. Seeking rain is only through supplication and seeking forgiveness." In summary, seeking rain merely by supplication after prayers is legitimate according to the majority of the four Madhhabs and the Zahiriyyah, and there is no harm in repeating the supplication three times. If the Imam encourages the people after the prayer and each person supplicates for themselves, or he supplicates for them and they say "Ameen," then there is no objection.