What is the difference between a second wife and the child about whom Allah Almighty said: "And do not kill your children for fear of poverty"? Is the provision for a second wife the same as the provision for a child, such that it is not a condition for marrying her that a man be financially well-off?

It is forbidden to kill or assault children under the pretext of inability to provide for them, because they already exist and thus must be cared for. This is unlike marriage, which has not yet taken place. Whoever is financially unable to marry should be patient until Allah enriches him. Moreover, the Sharia (definition) has made marriage conditional upon financial capability and has commanded the incapable to practice abstinence. Furthermore, a poor person should not marry so as not to deceive the woman, and he has obligations such as the dowry and maintenance. Therefore, refraining from marriage due to financial inability cannot be compared to killing children due to poverty.