Afæstla

According to the Old English Dictionary:

afæstla

interj. O certainly! O assuredly! O certe :-- Afæstla, and hi lá hi, and wella well, and þyllíce óðre syndon Englisc interjectiones O certainly, and alas, and well well, and such other are English interjections, Ælfc. Gr. 48; Som. 49, 28. afæstla