ע"י מעשה באו מאי היא דההוא עגלא דהוו קא ממטו ליה לשחיטה אזל תליא לרישיה בכנפיה דרבי וקא בכי אמר ליה זיל לכך נוצרת אמרי הואיל ולא קא מרחם ליתו עליה יסורין
The Gemara stated that Rabbi Yehuda HaNasi’s suffering came upon him due to an incident. What was that incident that led to his suffering? The Gemara answers that there was a certain calf that was being led to slaughter. The calf went and hung its head on the corner of Rabbi Yehuda HaNasi’s garment and was weeping. Rabbi Yehuda HaNasi said to it: Go, as you were created for this purpose. It was said in Heaven: Since he was not compassionate toward the calf, let afflictions come upon him.