μυθητάς

From LSJ

Κύριε, βοήθησον τὸν δοῦλον σου Νῖλον κτλ. → Lord, help your slave Nilos ... (mosaic inscription from 4th-cent. church in the Negev)

Source

Russian (Dvoretsky)

μῡθητάς: οῦ ὁ дор. = *μυθητής.