Matthew 10:26 - Albert Barnes' Notes on the Bible

Fear them not ... - He encouraged them by the assurance that God would protect them. and that their truth and innocence should yet be vindicated. It is probable that the declaration, There is nothing covered, etc., was a proverb among the Jews. By it our Saviour meant that their “innocence,” their “principles,” and their “integrity,” though then the world might not acknowledge them, in due time would be revealed, or God would vindicate them and the world would do them justice. They were, then, to be willing to be unknown, despised, persecuted for a time, with the assurance that their true characters would yet be understood and their sufferings appreciated.