Or HaChaim on Genesis 26:12/אור החיים על בראשית כ״ו:י״ב

1 מאה שערים, ויברכהו. one hundred fold; G'd blessed him. Since we have a general rule that anything that is measured does not qualify for a blessing, the Torah here informs us that G'd blessed Isaac's harvest even though the amount of his harvest had been measured. The Torah also wanted to tell us that despite the phenomenal success of Isaac as a farmer during a famine he did not suffer the effects of an evil eye of anyone who was jealous of his success.