Is it permissible to state a false cost basis by deducting a known profit from the subsequent purchase price in a Murabaha sale?

Chapter on Selling the Musarrah (Animal with milk retained in udder)

Al-Mughni

Book of Sales

Book 12 · Issue 2 · Bab 5

Open in Qurani

Primary text

It is impermissible to state that the item was purchased at the lower, post-profit deducted price (e.g., stating the cost is five when it was ten), as this constitutes a lie, which is forbidden. Such a statement renders the transaction equivalent to including undisclosed ancillary costs like tailoring or shearing in the stated cost price.

Supporting text

The counter-argument that this deduction accurately reflects the current cost basis is rejected, as the profit in the first contract was established in a prior, separate transaction, not as an intrinsic cost like labor or increase in value (like offspring or fruit) relating to the subsequent sale.