What is the meaning of the Prophet's saying, upon him be peace and blessings: "May your hands be soiled with dust, and how can her child resemble her?" to Umm Sulaym when she asked about a woman's wet dream?

This hadith is part of an agreed-upon hadith, and the wording from Bukhari, transmitted on the authority of Umm Salamah, states that Umm Sulaym asked the Prophet, peace and blessings be upon him, whether a woman is required to perform ghusl if she experiences a wet dream. He replied: "If she sees water." Umm Salamah then covered her face in astonishment, saying: "Does a woman have a wet dream?" The Prophet, peace and blessings be upon him, said: "Yes, may your right hand be soiled! Then what makes her child resemble her?" The phrase "تربت يمينك" (may your right hand be soiled) means 'may you become poor'; it is a word of admonition, not a curse. The hadith indicates that some women do experience wet dreams, and Umm Salamah's denial was due to the presence of semen. The Prophet, peace and blessings be upon him, responded by explaining that resemblance comes from the mixing of the two waters: if her water (fluid) prevails over the man's water, the child will resemble its maternal relatives, and if the man's water prevails over hers, the child will resemble its paternal relatives.