And when they saw him, they worshipped him: but some doubted. But some doubted - That is, Thomas only at first doubted. The expression simply intimates, that they did not all believe at that time. See the same form noticed on Matthew 26:8 (note), and Matthew 27:44 (note).
Related Commentaries of Matthew 28:17
Matthew 28:17
17 And when they saw him, they worshipped him: but some doubted.