Al-Kāfi - Volume 5 > The Need to Mention Conditions after Nikah
Hadith #2

2- عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنِ ابْنِ مَحْبُوبٍ عَنِ ابْنِ رِئَابٍ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ سَأَلْتُ أَبَا عَبْدِ اللهِ (عَلَيْهِ السَّلام) عَنْ قَوْلِ اللهِ عَزَّ وَجَلَّ وَلا جُناحَ عَلَيْكُمْ فِيما تَراضَيْتُمْ بِهِ مِنْ بَعْدِ الْفَرِيضَةِ فَقَالَ مَا تَرَاضَوْا بِهِ مِنْ بَعْدِ النِّكَاحِ فَهُوَ جَائِزٌ وَمَا كَانَ قَبْلَ النِّكَاحِ فَلا يَجُوزُ إِلا بِرِضَاهَا وَبِشَيْ‏ءٍ يُعْطِيهَا فَتَرْضَى بِهِ.

2. A number of our people have narrated from Sahl ibn Ziyad from ibn Mahbub from ibn Ri’ab from Muhammad ibn Muslim who has said the following: “This is concerning my question before abu ‘Abd Allah, ‘Alayhi al-Salam, about the words of Allah, most Majestic, most Glorious, 4 . . . it is not harmful for you if you agree upon it after marriage.’ (4:24) He (the Imam) said, ‘Whatever they agree upon after marriage is permissible and whatever is before marriage is not permissible except with her agreement and with something given to her to make her agree.’”