Delaying the payment of the price and delivering the goods if the article is present and known, such as a house, a car or the like, which has been described beyond any misconception at the time of concluding the sale, is permissible unless the article is liable to Riba (usury). If this is the case, the exchange should be on the spot. It is related on the authority of
`Ubadah ibn Al-Samit (may Allah be pleased with him) that the Prophet (peace be upon him) said,
"Gold is to be paid for by gold, silver by silver, wheat by wheat, barley by barley, dates by dates, and salt by salt, like for like and equal for equal, payment being made hand to hand. If these classes differ, then sell as you wish as long as payment is made hand to hand."
Muslim in his Sahih (authentic book of Hadith) Muslim)
(Part No. 13; Page No. 160)
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.