א מוראדיגע מעשה מיט הגאון ר' חיים קנייבסקי שליט"א

R. Chaim told him to come back next year, when he's 3, the
time when the minhag is to cut the hair. The man replied that his son was just diagnosed with a brain tumor (rachmona litzlon), and the doctor said he has less than a year to live - could the Rebbi please give him a brocha to live out this year without much yisurin.

R. Chaim Kanievski took the boy to one of the rooms in his apartment, and a few minutes later came back and told the man to return next year for the upsheren.

The man didn't understand what transpired, and took his son home. The next day, at the scheduled doctor's visit to re-scan the brain, the  doctor couldn't find anything on the X-Ray, and told the man to come back tomorrow, as the X-Ray machine must be broken.

The next day nothing came up on the machine again, to the surprise of the staff, since earlier that morning it worked fine. They consulted with the other doctors, and concluded that the tumor is completely gone.

The father returned to R. Chaim, asking him what happened. R. Chaim answered that - as is well known - he makes a Siyum Hatorah every year. At this siyum, his family celebrates, and lets him bentch (mezuman) on a koys. When he took the boy to the room, he gave him to drink from some
of that wine - which was drunk over Kol HaTorah Kulah - this was the brocha that cur ed to young boy