Is it permissible to sit in the front rows of the mosque when they are vacant, or should they be left for the elderly? And does this fall under revering Allah Almighty?

The jurists differed regarding altruism in acts of worship. Some of them permitted it, while others deemed it reprehensible or forbidden. Al-Zarkashi said that altruism is of two types: that which pertains to matters in which the self has a share, which is desirable; and that which pertains to acts of worship, such as the first row (in prayer). Some jurists have declared the latter forbidden because the purpose of worship is glorification and veneration. As for consistently abandoning the first row and delaying from it, it may give the impression of a kind of asceticism regarding good deeds.