Nechama Leibowitz commented on the admonition in this week’s parasha that we should be “wholehearted with G-d”. She wrote that the opposite of wholehearted is a disharmony between the inner and outer self, and between words and deeds. She quoted from Bahya who wrote that when a person’s words are contradictory to their deeds, they can’t be trusted, and their sincerity is doubted. He extended this concept to the service of G-d, which similarly cannot be sincere if there is a contradiction between our hearts and our words, and our inner conscience and outer actions.
Bahya explained further that the concept included eliminating magical practices, and keeping away from sorcery and enchantments.
Nachmanides wrote that we should direct our hearts exclusively to G-d and not consult soothsayers nor believe their words would be authenticated. He quoted from the covenant made with Avraham “Walk before Me and be wholehearted” , to make the point that both admonitions epitomised the distinction between heathendom and the true faith, and negated superstition and soothsaying.
R’ Eli Munk quoted from Rashi who explained that we should not be concerned about what will happen in the future, and from King David who wrote that when there were no prophets, we should pray and calmly trust in the Lord.