Explanation:

- A waqf is a charitable endowment under Islamic law. It permits a person to dedicate part of their property for religious or charitable purposes.

- Without the heirs’ consent, a waqf will only take effect to a limited portion of the property.

- One-Third: The waqf can take effect only up to one-third of the property without needing the consent of the heirs.

- One-Fourth: This option is incorrect as it underestimates the allowed amount.

- One-Fifth: This option is inaccurate, allowing an even smaller proportion incorrectly.

- One-Sixth: The smallest share, also incorrect, doesn’t align with Islamic inheritance principles.