Why in 39:53 and 39:10 is the call to believers made on behalf of the prophet?

Verses 39:53 and 39:10 say: Why is there the word "Say" in these verses? It was possible to use direct appeal without it. > Say: “O My servants who have exceeded the limits against their souls! > Do not lose hope in Allah’s mercy, for Allah certainly forgives all > sins. He is indeed the All-Forgiving, Most Merciful."39:53 > Say: “O My servants who believe! Be mindful of your Lord. Those who do > good in this world will have a good reward. And Allah’s earth is > spacious. Only those who endure patiently will be given their reward > without limit.”39:10