Mishkat al-Masabih 4 Prayer كتاب الصلاة 886

وَعَن ابْن عَبَّاس قَالَ: صلى الله عَلَيْهِ وَسلم حِين كسفت الشَّمْس ثَمَان رَكْعَات فِي أَربع سَجدَات وَعَن عَليّ مثل ذَلِك. رَوَاهُ مُسلم

Ibn ‘Abbas said that when an eclipse of the sun took place, God’s Messenger prayed performing eight bowings and four prostrations. There is a similar tradition from ‘Ali. Muslim transmitted it.