Is a girl sinful if she refuses to marry a suitor due to his difficult financial situation, or must she accept him based on the saying of the Prophet, peace and blessings be upon him: "If there comes to you one whose religion and character you approve, then marry him off"?

There is no harm in rejecting a young man due to his financial situation, as the command in the aforementioned Hadith is for recommendation, not obligation.

However, if the young man is religious and of good character, it is advisable to accept him; in compliance with the prophetic command, to ease the burden of marriage expenses, and hoping for wealth from Allah. Allah Almighty says: "And marry the unmarried among you and the righteous among your male slaves and female slaves. If they should be poor, Allah will enrich them from His bounty, and Allah is all-Encompassing and Knowing."

It is recommended to consult wise people who know the young man and to seek Allah's guidance through Istikhara.