Not only expensive animals are sacrificed on the altar, but also inexpensive birds and even low-priced wheat flour. Even the simple offering of a poor person is no less pleasing before God than any other offering, and when he sacrifices something that is dear to him, it is considered as though he sacrificed his soul.

Rabbi Yohanan said: Any ordinary person who smells the odor of the burning wings of a bird is repulsed, and you say that it should be sacrificed on the altar? Why? So that the altar will be glorified with every part of the offering of a poor person [who cannot afford more than a bird]. There was an incident involving a certain woman who brought one handful of fine flour for a meal offering, and the priest belittled her and said: Look what they are sacrificing! Is there enough here to eat? Is there enough here to sacrifice? The priest saw a message in a dream: Do not belittle her. It is as though she is sacrificing her soul. (Vayikra Rabba 3)