to excuse one's sins, blaming them on something (see Molina)
Alonso de Molina:
itla itech nictlamia ynnotlatlacol. itla itech onictlami in notlatlacol. escusar sus pecados, echando la culpa a algo. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 43r. col. 1. Thanks to Joe Campbell for providing the transcription.