Then came the disciples to Jesus apart, and said, Why could not we cast him out?
Berean Study Bible (BSB) - Matthew 17:19 >Afterward the disciples came to Jesus privately and asked, “Why couldn’t we drive it out?”
Textus Receptus (TR) - Matthew 17:19 >Τότε προσελθόντες οἱ μαθηταὶ τῷ Ἰησοῦ κατ᾿ ἰδίαν εἶπον, Διὰ τί ἡμεῖς οὐκ ἠδυνήθημεν ἐκβαλεῖν αὐτό;