عَنْ أَنَسِ بْنِ مَالِكٍ رَضِيَ اللَّهُ عَنْهُ قَالَ مُطِرْنَا عَلَى عَهْدِ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ فَخَرَجَ فَحَسَرَ ثَوْبَهُ حَتَّى أَصَابَهُ الْمَطَرُ قَالَ فَقِيلَ لَهُ يَا رَسُولَ اللَّهِ لِمَ صَنَعْتَ هَذَا قَالَ لِأَنَّهُ حَدِيثُ عَهْدٍ بِرَبِّهِ
It is narrated from Sayyiduna Anas (may Allah be pleased with him), he says: During the time of the Messenger of Allah (peace and blessings be upon him), it rained. So the Prophet (peace and blessings be upon him) went outside, removed the cloth from a part of his body, until the rainwater touched that part. Someone asked: O Messenger of Allah! Why did you do this? The Prophet (peace and blessings be upon him) replied: Because it has just come freshly from its Lord.