Dua to say repeatedly during eclipse
اللّهُـمَّ اغفِرلي، اللّهُـمَّ إِنَّكَ أَمَرتَنا أَن...
اللّهُـمَّ اغفِرلي، اللّهُـمَّ إِنَّكَ أَمَرتَنا أَن نَدعُوكَ وَوَعَدتَنا أَن تَستَجيبَ لَنا
Allahumma ighfir lee. Allahumma innaka amartana an nadAAooka wawaAAdtana an tastajeebu lana
Translation
O Allah, forgive me. O Allah, You commanded us to supplicate to You and promised us that You would respond.
When to recite
Recited during the eclipse prayer. The Prophet made extensive supplication during the eclipse and urged the companions to make du'a and seek forgiveness throughout.
Source / Reference
Al-Bukhari 2/32, Muslim 2/620