Al-Kāfi - Volume 5 > The Need to Mention Conditions after Nikah
Hadith #1

1- عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ عَبْدِ اللهِ بْنِ بُكَيْرٍ قَالَ قَالَ أَبُو عَبْدِ اللهِ (عَلَيْهِ السَّلام) مَا كَانَ مِنْ شَرْطٍ قَبْلَ النِّكَاحِ هَدَمَهُ النِّكَاحُ وَمَا كَانَ بَعْدَ النِّكَاحِ فَهُوَ جَائِزٌ وَقَالَ إِنْ سُمِّيَ الأجَلُ فَهُوَ مُتْعَةٌ وَإِنْ لَمْ يُسَمَّ الأجَلُ فَهُوَ نِكَاحٌ بَاتٌّ.

1. Ali ibn Ibrahim has narrated from his father from ibn abu ‘Umayr from ‘Abd Allah ibn Bukayr who has said the following: “Any condition before marriage becomes invalid by marriage and the condition after marriage is permissible.’ He (the Imam) said, ’If time limit is mentioned it is al-Mut‘ah (advantageous marriage) and if time limit is not mentioned it is permanent.’”