What is the ruling on a man marrying a widow out of a desire to help her, and does such a marriage necessitate entry into Paradise, and has Islamic law stipulated conditions for a second marriage, given that it may threaten the stability of the first marriage?

Taking care of a widow and helping her carries great virtue and immense reward. Marrying a second wife is permissible if the husband is capable of acting justly. However, we advise the husband not to rush into marrying a second wife if he does not need to, especially if it would lead to his first wife's defiance (nushooz) or separation and family disunity. Instead, he can help the widow with his wealth and endeavor to marry her to another man. If the husband needs to marry a second wife, he should strive to convince his first wife and explain to her that it is not permissible for her to seek divorce (talaq) or annulment (khul') unless she is unable to uphold the boundaries of Allah with him due to intense jealousy.