ויקרא א, ט "אשה ריח ניחוח לה'"
Me’am Lo’ez: When we speak of appeasement with relation to G-d, we do not mean that G-d actually has pleasure from a sacrifice, or has any need for it. G-d’s pleasure is simply that we are doing His will. G-d is also pleased that He has prepared a remedy for the Evil Urge, repentance.
Zevachim 46: The Gemara explains that "rei'ach" is the requirement to place the body of the sacrifice upon the altar in a condition that it will emit a strong pleasing smell. Simply put, this means that it should be placed while it is raw. The ensuing smell will be somewhat like a barbequed meat smell, which is very pleasing (unless you are pregnant). This prohibits one to first broil the meat before he places it upon the altar.
Zevachim 46: "Nicho'ach" means that the meat should be offered with a specific intention. This is not that one gives HaShem great "nachas" with his actions, that HaShem enjoys the actual offering, akin to sinking one's teeth into a succulent steak. Rather, the intention is that HaShem should have great satisfaction with a ben Yisroel's fulfillment His wish of bringing the sacrifice.
Menachos 110b: We find this same expression in 1:9 by the wealthy man's sacrifice, a robust ox, and in 1:17 by poor man's offering, a pigeon, to teach us that whether one brings a massive offering or a minimal offering, either is pleasant for HaShem as long as the donor's heart is intent on serving HaShem. HaShem appreciates equally or even more so an act that is small but is a Herculean effort or sacrifice for the doer, as a large act that is done easily. LESSON: Do acts of kindness even if they are something very small, even if no one knows about them, and do them with NO FANFARE. Such acts are never insignificant in HaShem's eyes, and are sometimes greater than acts that are very conspicuous and/or have much fanfare.
Chidushei haRim: What smells so good to HaShem? What is the lesson from this allusion? The smell of something always tell one that it is there or is coming but not yet there quite yet. One cannot see it, but the fragrance tells you that very soon you will see it. A Korban is a turning point in a person’s ways. One accepts to do Teshuvah and wants genuine change. Thus, when we bring a Korban, HaShem “smells” the forthcoming future, a future devoid of sin.
Lubavitcher Rebbe: The purpose of the korbanos is that the action from below upwards should elicit a corresponding action drawing down from above. This is the ultimate goal of HaShem that there should be a dwelling place specifically in this world. This is the pleasure that HaShem desires that His Presence should be revealed in this world.
