Two super simple sunnahs of Our Beloved Prophet ﷺ when it would rain:
1 Ṣaḥīḥ al-Bukhārī, abwāb al-istisqāʾ b. mā yuqāl idhā maṭarat, 1032, Musnad Aḥmad, musnad ʿĀʾishah, 24144, 25570, 25863, Ṣaḥīḥ Ibn Ḥibbān, k. al-istiʿādhah b. dhikr al-amr b al-istiʿādhah, 1006; with ‘ ijʿalhu ’ Sunan al-Nasāʾī, k. al-istisqāʾ b. ʿadad al-maṭr, 1532, Muṣannaf Ibn Abī Shaybah, k. al-duʿāʾ b. mā yudʿā bih li al-rawḥ idhā habbat, 29224
2 Ṣaḥīḥ Muslim 898, Sunan Abī Dāwūd, k. Al-adab b. mā jāʾ fī al-maṭr, 5100, Musnad Aḥmad, musnad Anas, 12365; with ‘ innhu ’ Ibid. 13820, al-Sunan al-Kubrā li al-Nasāʾī, k. al-istisqāʾ b. Karāhiyyah al-istimṭār bi al-anwāʾ, 1850, Ṣaḥīḥ Ibn Ḥibbān, k. al-nujūm wa al-anwāʾ b. dhikr mā yustaḥabbu li al-marʾ al-istimṭār fī awwal mātr yajīʾ fī al-sanah, 6135, Mustadrak ʿalā al-ṣaḥīḥayn li al-Ḥākim, k. Al-adab, 7768, Musnad al-Bazzār, musnad abī ḥamzah, 6873, Muṣannaf Ibn Abī Shaybah, k. al-adab b. man kān yaqṭur fī awwal maṭrah, 26179