Musar do Ozeasza 14:9

The reason the categories of Mamzer, the Moabite, and Ammonite may not intermarry with Jewish girls is that inasmuch as their place in the scheme of things prior to their becoming converted was in an unholy domain, they are considered to remain under the influence of the forces governing that domain. It is they who symbolize the unholy union between Samael and Lilith. They produce children who do not grow up to embrace G–d's teachings. Ruth Rabbah comments that anyone who marries people who belong to these "peripheral" domains is the subject of the verse in Hoseah 5,7: "They have begotten alien children because they have broken faith with the Lord." When Israel concludes sacred marriages, however, the souls of Israel are elevated from a holy source in accordance with Hosea 14,9: "I become like a verdant cypress. Your fruit is provided by Me." There is an allusion here to the nobility of the souls of Israel originating in the Celestial Regions. [Presumably the fact that in nature a cypress is not a fruit-bearing tree. Ed.] The expression רענן used by the prophet means that the cypress keeps on producing fruit, similar to the meaning of Isaiah 43,5: "I (G–d) will bring your descendants from the East."

The mystical dimension of the procedure of חליצה or the levirate marriage between a childless widow and her brother-in-law, is very profound. I will proceed to explain the rules of such a marriage because they are discussed in this portion. Our subject revolves around the concept of reincarnation and the transmigration of souls. The ultimate purpose of marriage is the union of kindred souls. One must avoid being married to someone whose soul is not a kindred spirit if one wants to ensure that one will have children who are truly children of G–d and of whom it can be said as in Hosea 14,9: "your fruit is provided by Me (G–d)." From all this it is clear that man's purpose is to emulate the ways of G–d; if someone has no children he does not only die in this world but also has no life in the Hereafter if he had failed to endeavor to have G–d-fearing children in this world.