Gevurot Meyruach Hakodesh 21:13

Then Rav Sha'ul answered, What are you doing weeping and breaking my lev (heart)? For I am prepared not only to be bound but to die al kiddush ha-Shem in Yerushalayim, for haShem of the Rebbe, Melech HaMoshiach Adoneinu Yehoshua.