Is it considered a lie to write a multiplied price (e.g., 40 instead of 20) on a gift without mentioning the currency, while deluding the recipient that this is its real price?

In summary: Deceit is not lying, because lying is informing about something contrary to its reality, while the deceiver is silent, and no statement is attributed to a silent person. If the gift is intended for endearment or maintaining kinship ties, it is commendable. If it is intended as a recompense, it is permissible and carries no reward. If recompense is stipulated, it becomes a gift of recompense, and its ruling is that of a sale. Thus, it is valid if the recompense is known and the two عوضان (items exchanged) are not usurious. If it is given for an unknown recompense, it is void. If the gift is intended to receive more in return, there is no harm in it.