How could Moses write about his own death before it happened?
Because God inspired Scripture, leading every word, Moses could write his own obituary while still alive. He recorded his death as if it were past, demonstrating divine inspiration. This is the beauty of Scripture: God enabled Moses to literally write the account of his own death before it happened.
Les explains that God told Moses to write his own obituary and funeral while he was still alive. Moses wrote the whole account as if it were in the past. Les calls this the beauty of Scripture: God is leading every word, which is inspiration, so that Moses can literally write the account of his own death. This shows that Scripture is divinely superintended, not merely human composition.