matequia.

matequia. nino. (pret. oninomatequi.) lavarse las manos.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 52v. col. 2. Thanks to Joe Campbell for providing the transcription.

MAHTEQUIĀ vrefl to wash one’s hands / lavarse las manos (M) [(3)Cf. 98r, 127r, (3)Xp.58]. C contrasts this with the imperfect form of MĀTEQU(I) ‘to cut one’s hand.’ This would seem to be from MĀ(I)-TL ‘hand’ and ĀTĒQUIĀ ‘to sprinkle water on something,’ but the vowel length pattern is completely wrong. Even deriving it with MAH, the alternative stem of MĀ(I)-TL, and TĒQUIĀ ‘to sprinkle something,’ there remains a discrepancy. X has MĀ for MAH.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 131.