Parsha Mitzvot: Vayikra: Mitzvah 130 – Concept 363
“But if his means are insufficient for two turtledoves or for two young pigeons, then he shall bring, as his guilt-offering for having sinned, a tenth-ephah of fine flour for a sin-offering; he shall not place oil on it nor may he put frankincense on it, for it is a sin-offering.” (Leviticus 5:11) It is forbidden to put frankincense on the meal offerings of wrongdoers. (Rambam, HichotMa’aseh KaKorbanot – The Laws of The Sacrificial Procedure)
It is not poverty but sin which precludes the oil and the incense. In a condition of sin even riches would prevent the real feeling of happiness. (Rabbi Samson R Hirsch)