The general procedure of Vedic marriage is that a father offers his daughter to a suitable boy. That is a very respectable marriage. A boy should not go to the girl's father and ask for the hand of his daughter in marriage. That is considered to be humbling one's respectable position. Svāyambhuva Manu wanted to convince Kardama Muni, since he knew that the sage wanted to marry a suitable girl: "I am offering just such a suitable wife. Do not reject the offer, or else, because you are in need of a wife, you will have to ask for such a wife from someone else, who may not behave with you so well. In that case your position will be humbled."
Another feature of this incident is that Svāyambhuva Manu was the emperor, but he went to offer his qualified daughter to a poor brāhmaṇa. Kardama Muni had no worldly possessions—he was a hermit living in the forest—but he was advanced in culture. Therefore, in offering one's daughter to a person, the culture and quality are counted as prominent, not wealth or any other material consideration.