Sforno on Deuteronomy 32:34/ספורנו על דברים ל״ב:ל״ד

1הלא הוא כמוס עמדי, the meaning is similar to Isaiah 63,4 כיום נקם בלבי, “as the day of vengeance which I had kept hidden in my heart.” [the sins had to accumulate beyond reprieve before G’d carried out what had been at the back of His mind for a long time. Ed.]

2חתום באוצרותי, sealed away securely. Compare Daniel 12,9 כי סתומים וחתומים הדברים, “the matters are sealed and safely stored.”