I sold a piece of land. But the money for this is...

 Praise be to God, Lord of the worlds, and prayers and peace be upon His faithful Messenger, and after:

You must pay zakat on all the amount if the quorum is reached and a year has passed for it, because the installments that you take even if they are deferred are in the ruling on the debt that is required to be paid, so zakat is paid.

God knows best and wisest.