Al-Adab Al-Mufrad, Book 33, Hadith 767 (English) ⓘ
Ibn 'Abbas said, "The rainbow is security for the people of the earth that they will not be drowned. The Milky Way is the door of the heavens and forms a furrow through it."
حَدَّثَنَا عَارِمٌ، قَالَ: حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ أَبِي بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ: الْقَوْسُ: أَمَانٌ لأَهْلِ الأَرْضِ مِنَ الْغَرَقِ، وَالْمَجَرَّةُ: بَابُ السَّمَاءِ الَّذِي تَنْشَقُّ مِنْهُ
also referenced under: Hadith 767 (Reference) & Book 33, Hadith 14 (In-Book)