Which law to obey

This is from Tolstoy in his work "My Religion"

One day I was walking (in Moscow) in the Borovitskiya Gates. At the gates an old lame beggar was sitting, with a dirty cloth wrapped about his ears. I was just taking out my purse to give him something. At the same moment down from the Kremlin ran a gallant ruddy-faced young soldier, a grenadier in the crown tulup. The beggar, on perceiving the soldier, arose in fear, and ran with all his might toward the Alexanderovsky Park. The grenadier chased him for a time, but not overtaking him, stopped and began to curse the poor wretch because he had established himself under the gateway contrary to regulations. I waited for the soldier. When he approached me, I asked him if he knew how to read. “Yes; why do you ask?”

“Have you read the New Testament?”

"I have."

“And do you remember the words, ‘If thine enemy hunger, feed him’….?”

I repeated the passage. He remembered it, and heard me to the end, and I saw that he was uneasy. Two passers-by stopped and listened. The grenadier seemed to be troubled that he should be condemned for doing his duty in driving persons away as he was ordered to drive them away. He was confused, and evidently sought for an excuse. Suddenly a light flashed in his intelligent dark eyes; he looked at me over his shoulder, as if he were about to move away.

“And have you read the military regulation?” he asked.

I said that I had not read it.

“Then don’t speak to me,” said the grenadier, with a triumphant wag of the head, and buttoning up his tulup he marched gallantly to his post.