|Art: Roxana Muchnik|
And if a [poor] person brings a meal offering to the Lord, his offering shall be of fine flour. He shall pour oil over it and place frankincense upon it. Vayikra 2:1
Unlike a wealthy person, who is able to give voluntary offerings in the Temple from expensive animals and birds, the poor man is only able to offer flour. Nevertheless, the Torah attributes more significance to the poor man's offering, as Rashi writes "I consider it as if he has sacrificed his very soul!"
This is because the wealthy man's offering is inevitably connected with a certain amount of self-satisfaction, at the thought of bringing one of the most expensive and impressive sacrifices. The poor man, however, could not possibly be proud of his meagre offering, so his is the most genuine offering of all, dedicated to G-d amidst feelings of humility. Thus, to him, G-d says ''It is as if he has sacrificed his very soul!"
Source: Likutei Sichos Lubavitcher Rebbe