Is it a condition for purifying the share before selling it that the capital itself be purified, such that it is sold after purification and the entire capital is disposed of?

It is not obligatory for the purification and removal of the unlawful portion from the lawful to be from the very asset intended for purification. It is permissible to remove this proportion from another asset. This applies to purifying impure stock dividends or their proceeds if sold. It is obligatory to dispose of the unlawful and doubtful proportion in every profit, whether it is operational profit or profit resulting from buying, selling, and speculation. This is because the forbidden portion may result from interest or from buying and selling associated with that forbidden portion.