The Rebbe's Previous Life

The Rema Mipano5 writes that Rav Shmuel Bar Shilas was a gilgul of the judge (one of the shoftim) Shamgar ben Anas and therefore he was a מלמד תינוקות, a Rebbe of children who teaches Torah.

A hint to this is found in וַיַּךְ אֶת־פְּלִשְׁתִּים שֵׁשׁ־מֵאוֹת אִישׁ בְּמַלְמַד הַבְּקָר. Shamgar killed the Philistines six hundred men with an ox-goad.6 The word בקר can be understood as a Rebbe of children who teaches Torah alluding to that in the future he would be reincarnated as Rav Shmuel Bar Shilas who taught children Torah.7 The word בקר hints to what Rav told Rav Shmuel Bar Shilas that if a child is six years old, accept him and stuff him like an ox )9(בקר.8