In murabahah, goods can still be transferred at the first price plus some profit even when the disclosed cost was wrong; the buyer nevertheless receives an option because of the misleading disclosure.
Tawliyah specifically promises transfer without an increment over the first price. Keeping a dishonest excess would contradict that characterization.
This distinction explains why Abu Hanifah assigns an option in murabahah but a price deduction in tawliyah.
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Murabahah and Tawliyah: Cost, Profit and Misstatement
In murabahah, goods can still be transferred at the first price plus some profit even when the disclosed cost was wrong; the buyer nevertheless receives an option because of the misleading disclosure.
Tawliyah specifically promises transfer without an increment over the first price. Keeping a dishonest excess would contradict that characterization.
This distinction explains why Abu Hanifah assigns an option in murabahah but a price deduction in tawliyah.