But the Lord was angry with me on your account, and would not listen to me; and the Lord said to me, ‘ Enough! Speak to Me no more of this matter. Deuteronomy 3:26

Sin always brings irrevocable consequences. While it can be forgiven and forgotten by God, some opportunity is lost, some more perfect way is forfeited. The refrain goes something like this: “I will never be able to…” It might be a seared conscience, loss of total confidence, or financial loss. It’s like the description of salvation as a taste that will henceforth always be recognized (Hebrews 6:4). Sin at the very least taints and taunts from the haunts of the past. So important then is self-control under the Spirit’s power. Ask Moses.