Komentarz do Wyjścia 16:16

עמר — the name of a measure.

'זה הדבר אשר צוה ה, and in the morning you will eat bread (food) to satisfy yourselves. (compare verse 12)

איש לפי אכלו, everyone according to his capacity to eat. This does not refer to the individual's eating capacity but to the number of people in his household. The reason the Torah speaks about a single individual's capacity to eat, i.e. אכלו is because the head of the household determines how many people depend on him. Nonetheless he could collect on behalf of people who though dwelling in his tent did not depend on him. You will find confirmation of this approach when you study the way the Torah describes who collected how much. In verse 17 we are told that each person had collected an amount corresponding to individual need, whereas in verse 16 we are told that after they measured what they had collected they found that each one had collected exactly one Omer per head. If that is all that mattered, why did the Torah have to add: "according to the number of persons in his tent?" Clearly, the Torah wanted to include persons in a tent for whose maintenance the head of the household was not responsible. You will find studying what the Talmud Yuma 75 has to say on the subject very illuminating.