Mark 1:40–45
40 And a leper came to him, imploring him, and kneeling said to him, “If you will, you can make me clean.” 41 Moved with pity, he stretched out his hand and touched him and said to him, “I will; be clean.” 42 And immediately the leprosy left him, and he was made clean. 43 And Jesus sternly charged him and sent him away at once, 44 and said to him, “See that you say nothing to anyone, but go, show yourself to the priest and offer for your cleansing what Moses commanded, for a proof to them.” 45 But he went out and began to talk freely about it, and to spread the news, so that Jesus could no longer openly enter a town, but was out in desolate places, and people were coming to him from every quarter.
If you read v. 41 in the NIV it will say "Jesus was indignant" instead of "moved with pity". That's because there is a disagreement in the manuscripts that we have. Of the oldest and therefore, more valued manuscripts, 2 from the 5th c. CE say "indignant". However, 2 that date to the 4th c. CE say "pity, compassion". Generally, when there is a disagreement like this the older manuscripts carry more weight. Therefore, it is more likely that "pity" is the correct word here as almost all of the major translations indicate (ESV, NLT, NKJV, KJV, RSV). To help put your mind at ease, there are no textual variants like this one that would change any of the major doctrines of the Christian faith.
If "indignant" is correct then it likely isn't suggesting that Jesus was indignant with the man with leprosy for breaking social convention or his boldness because Jesus proceeds to touch him and to heal him. It would likely mean that he was indignant with the misery of the leper or the social codes that required his situation. In any case it's obvious that Jesus took compassion on him whether or not his first reaction was indignation because he proceeded to heal him. However, "pity" is likely the original. Your Bible will have a note on it, as it will for most disputed words like this, to be sure to notify you of any major disagreement in the text.
The word translated "pity" in v. 41 is often translated as "compassion" as well. It occurs 3 other times in the gospel of Mark and, in each instance, the ESV translates it "compassion". Compassion is a marker of Jesus' ministry. In 6:34 he has compassion on a crowd because they are "like sheep without a shepherd." In 8:2 he again has compassion on a crowd because they had been with him 3 days and had nothing to eat. In 9:22 he is asked to have compassion on a boy possessed by an evil spirit and, of course, he does.
Jews in Jesus' day who were versed in the OT would've certainly recognized Jesus' compassion as a primary characteristic of YHWH. In Exodus 34:6 when God declares his name to Moses he says, "The LORD, the LORD, the compassionate and gracious God..."(NIV). Compassion is listed first among God's characteristics, emphasizing this quality. God's compassion can be seen throughout the OT in his constant faithfulness to the people of Israel. Jesus here picks up the mantle and demonstrates the compassion of YHWH to those in need.