Rav Yankele of Pshevorsk zy”a related that the Sar Shalom of Belz zy”a once was speaking about the sanctity of Lag B’Omer, when his son, Rav Zundel, said, “I know.”
His father, turned to him and said, “Nu...” (Prompting him to speak.)
Rav Zundel said, “It is as great a day as Yom Kippur!”
The Sar Shalom responded, “That is correct!”