In this passage we are commanded “You shall not give false testimony against your neighbour”. God hates it. This command is repeated throughout the Bible and we should not ignore it.
As people, we find lying quite an easy thing to do. It all went wrong in the Garden of Eden with a lie (Genesis 3 v 4). People still believe Satan’s lie today and do not believe the truth of God in Jesus. Lying always points us away from God to something else and we start worshipping other things. Everything works better with truth, we need it. Slander, deceit and flattery are all lying and a distortion of the truth.
1 John 2 v 4 also reminds us “Whoever says, “I know him” but does not do what he commands is a liar, and the truth is not in that person.”