Even light words of Chazal should be taken seriously, but especially when they are chosen purposefully.
This is hinting at the incident of the golden calf, and how the the firstborns were sent away from God's service and the Levim were chosen.
He led an ox - משך תורא
When the Jews were drawn after the golden calf which took them away from the ...
It’s called Seasonings of the Torah:
Fascinating Parashah allusions based on letters, vowels, numbers and history
Here is the book’s summary from ArtScroll.com
Enter the world of deep Torah insights through the eyes of Hagaon Harav David Feinstein. The Rosh Yeshiva of Mesivtha Tifereth Jerusalem, Rabbi Feinstein is one of the most distinguished halachic ...