Torah Temimah points to Kiddushin 30a (Rav Safra in the name of R’ Yehoshua ben Chananya: “veshinantam” read as “veshilashtam” — divide one’s years into thirds).
English: Rav Safra said in the name of R’ Yehoshua ben Chananya: What is meant by “veshinantam”? Do not read “veshinantam” but “veshilashtam” — a person should always divide his years into thirds: one third in Scripture, one third in Mishnah, one third in Gemara.
On the daf / in context: The derasha is an asmachta that establishes the ideal balanced curriculum of lifelong Torah study.
Type of Learning
Al tikrei (do not read… but…) — “veshinantam / veshilashtam.”
What Is Learned
A person should allocate his study time in equal thirds among Scripture, Mishnah, and Gemara.