Musar zu Bereschit 25:1

The incense-offering is the mystical element which establishes the connection between the "lower" and the "upper" domains of this universe. Rashi also explains the word קטורת as identical with the alternate name of Hagar, i.e. קטורה, to mean that her deeds were comparable to an incense offering because she "tied up" her door [euphemism for her vagina Ed.] and did not remarry until Sarah had died and Abraham was free to marry her (Genesis 25,1). Our sages suggest that Nadav and Avihu entered the Holy of Holies in order to teach a lesson concerning the mystical dimension of the incense-offering. They wanted to demonstrate that G–d anxiously awaits the prayers of the righteous. All of these notions are alluded to in Psalms 141,2: תכון תפלתי קטורת לפניך, "Take my prayer as an offering of incense before You." The subject of prayer teaches us the mystical dimension of the משפיע and the מושפע The latter prays with his eyes facing downwards while his heart is turned upwards toward G–d, the cause who turns His attention to what happens "down" here in our world. We in our hopes pour out our hearts heavenwards for He is the עילה, cause, whereas we are the עלולים, effects.