It is very important when reading the Bible to ignore the chapters.
When God gave us the Scriptures, he didn't give them in chapters. There are a few places where there are natural divisions....the Psalms is the most obvious. But they are not even called chapters (some preachers need to realize that). The story of Jesus and the widow's two mites is a perfect example of misrepresenting the Scriptures because of chapter divisions. Here is the story:
Then in the audience of all the people he said unto his disciples, Beware of the scribes, which desire to walk in long robes, and love greetings in the markets, and the highest seats in the synagogues, and the chief rooms at feasts; which devour widows' houses, and for a show make long prayers: the same shall receive greater damnation.
And he looked up, and saw the rich men casting their gifts into the treasury. And he saw also a certain poor widow casting in thither two mites. And he said, Of a truth I say unto you, that this poor widow has cast in more than they all: for all these have of their abundance cast in unto the offerings of God: but she of her penury has cast in all the living that she had.
Most of us "know" that Jesus praised the widow for her sacrificial giving. But if you read the passage, that is not what happened.
Jesus was in the middle of warning his disciples and those around him about the scribes. They love public greetings, seats of honor, chief rooms, but their prayers are a show; they devour the income, yes, even the houses of widows; and they will receive greater damnation. Then, just like someone planned it, he looks up and there are rich men putting lots of money into the treasury. And, coincidentally, a widow is also putting money into the treasury. She was poor and only had two mites to give. (I wonder why? Maybe the context will tell us.)
Jesus tells the disciples, the crowd, and us, "That widow with just two mites has given more than all of the rest of them put together." He did not praise her sacrifice. He did not condemn her sacrifice. He didn't say anything about sacrifice. He did not encourage everyone there to go and empty all that they had into the treasury so that they could be like the widow. His one short statement taught us how to measure someone's contribution (regardless of the circumstances). He taught us that the size of the contribution is measured by how much each contributor has left.
There is more righteous indignation and scorn in this passage than praise. There might be pity on the widow, but there is definitely scorn of those that think they are giving a lot when they really have tons left over. And there's indignation or even anger that the reason they have so much is because they "devour widows' houses."
When you ignore the "Chapter 21," Jesus' seemingly pointless statement makes sense right within the context. There is no need to grab meaning from other parts of the Bible to figure it out.