His statement, “whichever is more advantageous to the poor”: What is meant is whichever is more advantageous to those entitled to zakah, for the recipients of zakah include the poor, the needy, those employed to administer it, and those whose hearts are to be reconciled. Had the author said, “those entitled to zakah,” it would have been more comprehensive. However, he mentioned the poor because they are the most common category.
His statement, “in gold or silver”: Gold refers to dinars, and silver to dirhams. Thus, if we appraise the goods and their value does not reach the minimum taxable threshold when calculated in gold dinars, but does reach the threshold when calculated in silver dirhams, we use the silver standard. That is, if these goods are worth two hundred dirhams and fifteen dinars, then zakah is not due if we use the dinar standard, whereas it is due if we use the dirham standard. What is more advantageous to the poor, therefore, is to appraise them in silver. The reverse also applies: if these goods are worth twenty dinars or one hundred and fifty dirhams, they are assessed in gold dinars, because that is more advantageous to those entitled to zakah.
If someone were to ask: How can you adopt what is more advantageous when the Prophet, peace and blessings be upon him, said to Mu'adh, may Allah be pleased with him, “Avoid the choicest of their wealth, and fear the supplication of the oppressed”? (1)
The answer is that there is a difference between the two cases. The hadith of Mu'adh, may Allah be pleased with him, concerns a case in which zakah has become due; one should not then take from the best of a person’s wealth. In the present case, however, zakah becomes due according to one of the two monetary standards but not according to the other. Therefore, we adopt the more cautious course: whichever standard brings the value to the minimum taxable threshold—gold if it is gold, and silver if it is silver.