If you sell furniture in cash or in installments while possessing it, then the transaction will be valid.
sell furniture in cash or on deferred payment while you do not possess it, then this transaction will be invalid. The Prophet (peace be upon him) forbade a person selling what they do not posses in the Hadith reported by
Hakim ibn Hizam. He said:
"Do not sell what you do not possess!"
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.