Wed Sotah 37

Binyamin jumped in first and Yehudah was throwing stones.

Tosfos quotes Michltin that gives a parable. This is similar to a king that gives instructions to his younger son to wake him at dawn. He then instructed his alder son to wake him three hours in the day. When the younger son came to wake his father, the older son protested, until the commotion woke the father. The father said since you both did this for my sake, I will reward you both.

(I assume that there was a basic argument between Binyamin and Yehudah when to jump in, and Yehudah was waiting for the more apt time and thus protested Binyamin for jumping in early.)