Commentaire sur Le Lévitique 26:28

ויסרתי, same as Deuteronomy 8,5 כאשר ייסר איש את הנו, “as a father who disciplines his son.” The word occurs in this sense also in Deuteronomy 21,18 ויסרו אותו, “after they disciplined him.” (physical punishment.) Similar constructions are found with the root ישב, as in Ezekiel 25,4 וישבו בך טירותם, “they will establish their palaces within you.”

ויסרתי, “I will chastise;” the vowels here are: sh’va, followed by chirik. [strong conjugation piel. Ed.]