There once was a 94-year-old rabbi in the 1890's in a small shtetle in Poland whose worn-out body began to surrender. The shtetle doctor prescribed for him a shot of whiskey three times a day, to relax him.
However, not to be lured into worldly pleasures, he declined. But the doctor heard that the rabbi loved milk. So he instructed the rabbi’s wife to spike his milk three times a day.
Eventually, the elderly rabbi approached his final hour. As several of the townsfolk gathered around him at his bedside, the townsfolk asked if there were any words of wisdom the rabbi wanted to leave to the people in the town.
"Oh, yes," he replied. "Never sell that cow!"