Torah Temimah points to the Amoraic dispute on how many negative commandments are implied by the triple language of the verse (Reish Lakish / Ravina / R’ Nachman bar Yitzchak).
English: Reish Lakish said: Anyone who forgets one item of his learning violates a negative commandment… Ravina said: “hishamer” and “pen” are two separate lavin. R’ Nachman bar Yitzchak said: he violates three lavin, as it is said “hishamer lecha u-shmor nafshekha me’od pen tishkach.”
On the daf / in context: The multiple prohibitive expressions are counted as multiple distinct negative commandments against willful forgetting of Torah.
Type of Learning
Diyuk of the triple language (“hishamer / u-shmor / pen”) as multiple distinct lavin.
What Is Learned
Willful forgetting of Torah is prohibited by as many as three separate negative commandments derived from the language of this verse.