A person is not allowed to take a mother bird while she is on her young, even if they need the mother bird to perform the mitzvah (commandment) conclusion ceremony. When a person has tzara'at (skin affliction), they have to go through a series of different processes in order to purify themselves. As part of the process, they have to take two kosher (ritually fit) birds and slaughter them, one of them over a cup of spring water. The other one is dipped into the water and the blood and used to sprinkle onto the metzora (person with tzara'at). So this is considered to be a very great mitzvah, person's enabling the living back together with his family. The metzora is impure and is going to be pure once more, but they still cannot take the mother bird while she's with her young in order to perform this great ceremony. It doesn't enable him to violate this halacha (Jewish law).
And a lesson that we learn about from the to conclude: We see this easy mitzvah, sending away a mother bird, which has barely any loss of money involved. The Torah still promises it's going to be good for you and it will prolong your days. It promises a great reward for this small mitzvah that doesn't cost much. It doesn't take much effort in order to get it done. How much more so will there be a beracha (blessing), will there be tremendous reward for the more difficult mitzvot of the Torah, where you have to put forth a great effort and a greater expense. The beracha will rest on that person on an even greater level.