Trust ye not in a friend, put ye not confidence in a guide: keep the doors of thy mouth from her that lieth in thy bosom.
Trust ye not in a friend - faith is kept nowhere: all to a man are treacherous (Jeremiah 9:2-6). When justice is perverted by the great, faith nowhere is safe. So, in Gospel times of persecution, "a man's foes (are) they of his own household" (Matthew 10:35-36; Luke 12:53).
Put ye not confidence in a guide - a counseler (Calvin) able to help and advise (cf. Psalms 118:8-9, "It is better to trust in the Lord than to put confidence in man. It is better to trust the Lord than to put confidence in princes;" Psalms 146:3). Micah means the head of your family, to whom all the members of the family would naturally repair in emergencies. Similarly the Hebrew х 'aluwp (H441)] is translated in Joshua 22:14 "an head of the house," and "chief friends" in Proverbs 16:28 (Grotius).
Her that lieth in thy bosom - thy wife (Deuteronomy 13:6, "the wife of thy bosom").