A prominent minhag on seder night is that the children "steal" the afikoman and hide it. What follows is the normal haggling process as the father agrees to buy a child a gift in return for the afikoman.
However, is the father allowed to specify a certain gift, or is this an issue because of
מִמְּצ֥וֹא חֶפְצְךָ֖ וְדַבֵּ֥ר דָּבָֽר
Nor look to your affairs, nor strike bargains (Yeshaya 58:13)
This concept is codified in Halacha e.g. refer to Mishneh Torah, Shabbos 24:1 and SA OC 306:1 as well as others.
