I have not sat with vain persons - That is, I have not been found among them; I have not made them my companions. See the notes at Psalms 1:1. The word “vain” here is in contrast with those who are sincere and true. The expression would be applied to people who are false and hollow; to those who have no sincerity or solidity of character; to those who are hypocrites and pretenders. The psalmist urges it as one evidence of his attachment to God that he had not been found among that class of persons, either as making them his companions, or as taking part with them in their counsels.
Neither will I go in with dissemblers - Neither will I walk with them; neither will I be found in their company. The word here rendered “dissemblers” means properly those who are “hidden” or “concealed;” then, those who hide their purposes or designs from others, or who conceal their real character and intentions. Thus used, the word denotes hypocrites, whose real character is “concealed” or “hidden” from the world. The psalmist says that he had not associated with such people, but that His companionship had been with the open, the frank, the sincere. On this he relied as one evidence of his piety; and this is always an evidence of true religion. See the notes at Psalms 1:1.