Is there a difference between the rich and the poor in paying the alms given at the end of Ramadan, and its value for each of them?

The student : I remember once, last year, we spoke with you about the topic of the alms given at the end of Ramadan. I said to you: meaning, in the alms given at the end of Ramadan, one should consider that the rich pays differently from the poor, so that we do not wrong the poor on the part of the rich, nor wrong the poor in his payment. I mean, this rich person must pay more in wheat, in the measure of dates, in the measure of raisins, in the measure of dates, because the rich has the means, so he must pay more than this estimate that we have set, meaning by the standard of barley or wheat. And the poor, when he wants to pay, we do not make him pay more than what he can afford, so that we give him the price of dried yogurt, or the price of wheat, and leave him from barley. So I detailed that day: considering this matter. Do you say it is obligatory? I mean, must the rich, by obligation, pay with dates and raisins, or is it voluntary?

The Shaykh : No, it is voluntary.
The student : Voluntary!

The Shaykh : It is a virtue.
The student : It is a virtue. It is better for him to pay more. Yes, may Allah reward you with good.

The Shaykh : And beware of that.