It's easy to say not to trust men and to rely on the Lord. Our Gor is a truthful and faithful God, we do know that, but when it comes to truly believe it, living in this world full of deceptions and lies, I think you have all the reasons to feel reluctant and scared.
I don't know if it's accurate to quote this verse in this specific matter, but this is one that helps me take courage and regain hope, when my heart feels weak and sad.
I think this refers to God always keeping His promises.