The Yahrzeit of Shemu’el haNavi
[A] custom arose, as recorded by the Radvaz, to come to Nabi Samwil, the traditionally identified location of his gravesite, tonight, on his yahrzeit. A bit north of Yerushalayim. And there children would get their first haircuts. When Shemu’el was weened, he was sent to the Mishkan to live. And he was a nazir, who did not cut his hair his entire life. So there is a logical connection between Shemu’el haNavi and haircuts. Also moved into the Mishkan after he was weened and he grew up there, thus giving the navi a connection to toddlers turning into boys, as well.