If angels could be jealous of men, they would be so for one reason: Holy Communion.Note that Kolbe does not say "the Mass." This is an important nuance, since he elsewhere said that the Mass reaches its culmination not in the Consecration but in the Communion (March 10, 1940). He is talking about what we Lutherans generally call the Distribution.
And if you're wondering, he really did say this, albeit in the equivalent of his Table-Talk. Jerzy Domanski translates the remark from the Ascetical Conferences of Father Maximilian Kolbe, from the Notes of those Who Heard Him (Niepolkalanow, 1976) where it is dated Dec. 18, 1938.