Will a person be rewarded for bequeathing his wealth to his brothers, sisters, and their children if he has no offspring, given that the wealth is the fruit of his toil and effort?

The deceased receives reward for the lawful wealth he leaves for his heirs, whether it was from his own earnings or acquired through permissible means like inheritance or gifts, and regardless of whether the heirs are his children, siblings, or others. This is supported by the Prophet's (peace and blessings be upon him) statement to Sa'd (may Allah be pleased with him): "It is better for you to leave your heirs wealthy than to leave them poor, begging from people. And indeed, whatever you spend of your expenditures, it is a charity." This indicates that his heirs remaining wealthy and independent of people is more comforting to him, and better for him in the Hereafter, bringing him greater reward. Thus, the reward is attained by him both in life and after death.