Aaron lifted up his hands toward the people and blessed them. He then descended, after having offered up the sin-offering, the ascent-offering, and the peace-offering.
Leviticus 9:22
The first stanza of the priestly blessing is, “May G-d bless you and watch over you,” which, as Rashi tells us, means, “May G-d bless you with abundance and watch over you so that no one steals your wealth.”
Spiritually, the abundance referred to here is our success in our efforts to refine ourselves and serve G-d wholeheartedly. This blessing needs to be guarded from being “stolen,” since the forces of negativity within us often try to sabotage the spiritual excitement that we generate in prayer, transforming it afterwards into righteous indignation or an awakening of physical desire. We therefore ask G-d to not only bless us with success in spiritual refinement and the experience of spiritual ecstasy, but also with the ability to properly focus it and channel it in pure and wholesome directions.
—from Daily Wisdom 3