Parashas Shemos · Passuk 1:9
וַיֹּ֖אמֶר אֶל־עַמּ֑וֹ הִנֵּ֗ה עַ֚ם בְּנֵ֣י יִשְׂרָאֵ֔ל רַ֥ב וְעָצ֖וּם מִמֶּֽנּוּ׃
And he said to his people: Behold, the people of the children of Israel are more numerous and stronger than we.
Torah Temimah points to Sotah 11a / Mechilta (verified).
תני, הוא התחיל בעצה תחלה, דכתיב ויאמר אל עמו\ldots הבה נתחכמה, לפיכך לקה הוא תחלה.
English: It was taught: He began the counsel first, as it is written “And he said to his people\ldots Come, let us deal wisely”; therefore he was struck first.
Custom — narrative sequence and measure-for-measure.
Chazal teach that the one who opens the counsel of harm is the first to suffer the corresponding punishment.