The recommended condition for the imam to be in if he goes out Sunan an-Nasa'i 1507
Arabic hadith text
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا عَبْدُ الْعَزِيزِ، عَنْ عُمَارَةَ بْنِ غَزِيَّةَ، عَنْ عَبَّادِ بْنِ تَمِيمٍ، عَنْ عَبْدِ اللَّهِ بْنِ زَيْدٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلماسْتَسْقَى وَعَلَيْهِ خَمِيصَةٌ سَوْدَاءُ .
Translation
It was narrated from Abdullah bin Zaid that
The Messenger of Allah (ﷺ) prayed for rain wearing a black khamisah.