After mentioning the torment that Allah has prepared for His miserable enemies who disbelieve in Him and in His Messengers, He mentions the condition of His happy, loyal friends who believe in Him and in His Messengers, adhere to the faith and perform the good deeds. This is the reason why the Qur'an was called Mathani, based on the correct opinion of the scholars. We will elaborate upon this subject later. Mathani means to mention faith and then disbelief, or vice versa. Or, Allah mentions the miserable and then the happy, or vice versa. As for mentioning similar things, it is called Tashabbuh, as we will come to know, Allah willing. Allah said,
﴿وَبَشِّرِ الَّذِينَ ءَامَنُواْ وَعَمِلُواْ الصَّـلِحَاتِ أَنَّ لَهُمْ جَنَّـتٍ تَجْرِى مِن تَحْتِهَا الأَنْهَـرُ﴾
(And give glad tidings to those who believe and do righteous good deeds, that for them will be Gardens under which rivers flow (Paradise)). Consequently, Allah stated that Paradise has rivers that run beneath it, meaning, underneath its trees and rooms. From Hadiths it is learned that the rivers of Paradise do not run in valleys, and that the banks of Al-Kawthar (the Prophet's lake in Paradise) are made of domes of hollow pearls, the sand of Paradise is made of scented musk while its stones are made from pearls and jewels. We ask Allah to grant Paradise to us, for verily, He is the Most Beneficent, Most Gracious.
Ibn Abi Hatim reported that Abu Hurayrah said that the Messenger of Allah said,
«أَنْهَارُ الْجَنَّةِ تَفَجَّرُ تَحْتَ تِلَالٍ أَوْ مِنْ تَحْتِ جِبَالِ الْمِسْك»
(The rivers of Paradise spring from beneath hills, or mountains of musk.)
He also reported from Masruq that `Abdullah said, "The rivers of Paradise spring from beneath mountains of musk.''