According to Thomas of Celano who was Francis' earliest biographer, Francis "often freed lambs and sheep from the threat of slaughter because of the graciousness he felt towards the simplicity of their nature." Francis showed compassion to all creatures including sheep and lambs as the stories testify.
One day "Francis was travelling through the Marches with another brother when he came across a man on his way to market. The man was carrying over his shoulder two little lambs bound and ready for sale. When blessed Francis heard the bleating lambs, his innermost heart was touched and, drawing near, he touched them as a mother does with a crying child, showing his compassion. "Why are you torturing my brother lambs," he said to the man, "binding and hanging them in this way?" "I am carrying them to market to sell them, since I need the money," he replied. Francis asked: "What will happen to them?""Those who buy them will kill them and eat them," he responded. At that, Francis said: "No, this must not happen! Here, take my cloak as payment and give me the lambs." The man readily gave him the little lambs and took the cloak since it was much more valuable.
Francis, having taken the lambs, now was wondering what he should do with them. Asking advice from the brother who was with him, he gave them back to that man, ordering him never to sell them or allow any harm to come to them, but instead to preserve, nourish, and guide them carefully."
- from The Life of St. Francis by Thomas of Celano, 1229