"As much as his soul will desire"

Al-Busayree narrates with a Mursal chain:

وعن الهيثم الطائي ، وسليم بن عامر ، أن النبي صَلَّى الله عَلَيه وسَلَّم سُئِل عن البضع في الجنة ، فقال : نعم بقبل شهي ، وذكر لا يمل ، وإن الرجل ليتكئ فيها المتكأ مقدار أربعين سنة لا يتحول عنه ولا يمله ، يأتيه فيها ما اشتهت نفسه ولذت عينه. رواه الحارث بن أبي أسامة ، مرسلاً. وله شاهد من حديث أبي سعيد الخدري ، رواه ابن حبان في صحيحه

ENGLISH:

"And on the authority of Al-Taa'ie, and Saleem bin Umar, that the Prophet was asked regarding sexual intercourse in Paradise, and he said: "Yes, it will be with a pleasant caress, and a member which does not tire. And verily, a man will have sex with a woman for forty years, (during this time) he will not move away and nore will he tire! He will have sexual intercourse as much as his soul will desire and his eyes will find pleasure in". Mursal, and it's narrators are trustworthy". This has been narrated by Al-Haarith bin Abi Usamah, as mursal. Wa lahu shahid min hadith abi sa'eed al-khudri, and Ibn Hiban collected this narration in his Sahih".

["Ithaaf al-Khayrah", 7867].