Authentic
graded by Al-Albani
Mishkat al-Masabih 5496
وَعَنْهُ أَنَّ ابْنَ صَيَّادٍ سَأَلَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنْ تُرْبَةِ الْجَنَّةِ. فَقَالَ: «در مَكَّة يبضاء ومسك خَالص» . رَوَاهُ مُسلم
He told that Ibn Sayyad asked the Prophet about the soil of paradise and that he replied it was a white, sifted flour and pure musk. Muslim transmitted it.
Cited in Mishkat al-Masabih (No. 5496).