It is narrated from Sayyiduna Anas (may Allah be pleased with him), he said: We were with the Prophet (peace and blessings of Allah be upon him) when it started to rain. The Prophet (peace and blessings of Allah be upon him) removed his blessed garment from his body until the rain touched his body. We said: O Messenger of Allah! Why did you do this? He (peace and blessings of Allah be upon him) said: "Because it has just now come from its Lord."
Hadith Referenceالادب المفرد / كتاب / 571
Hadith Gradingالألبانی:صحيح
Hadith Takhrij«صحيح : أخرجه مسلم ، كتاب صلاة الاستسقاء : 898 و أبوداؤد : 5100 - انظر ظلال الجنة : 622»
Explanation & Benefits
Shaykh Maulana Usman Muneeb
Benefits and Issues: From this, it is understood that at the time of rainfall, removing one's garment from the body and directly benefiting from the rain, letting it touch the body, is Sunnah. Likewise, supplications (du'a) are accepted at the time of rainfall. Therefore, one should take advantage of this opportunity and make supplication at that time.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 571