Conditions contrary to Allah’s Book are nullified

عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى اللّٰهُ عنها ـ قَالَتْ جَاءَتْنِي بَرِيرَةُ فَقَالَتْ كَاتَبْتُ أَهْلِي عَلَى تِسْعِ أَوَاقٍ فِي كُلِّ عَامٍ وَقِيَّةٌ، فَأَعِينِينِي‏.‏ فَقُلْتُ إِنْ أَحَبَّ أَهْلُكِ أَنْ أَعُدَّهَا لَهُمْ وَيَكُونَ وَلاَؤُكِ لِي فَعَلْتُ‏.‏ فَذَهَبَتْ بَرِيرَةُ إِلَى أَهْلِهَا، فَقَالَتْ لَهُمْ فَأَبَوْا عَلَيْهَا، فَجَاءَتْ مِنْ عِنْدِهِمْ وَرَسُولُ اللَّهِ صَلَّى اللّٰهُ عَلَيْهِ وَسَلَّم جَالِسٌ، فَقَالَتْ إِنِّي قَدْ عَرَضْتُ ذَلِكَ عَلَيْهِمْ فَأَبَوْا، إِلاَّ أَنْ يَكُونَ الْوَلاَءُ لَهُمْ‏.‏ فَسَمِعَ النَّبِيُّ صَلَّى اللّٰهُ عَلَيْهِ وَسَلَّم فَأَخْبَرَتْ عَائِشَةُ النَّبِيَّ صَلَّى اللّٰهُ عَلَيْهِ وَسَلَّم فَقَالَ ‏”خُذِيهَا وَاشْتَرِطِي لَهُمُ الْوَلاَءَ، فَإِنَّمَا الْوَلاَءُ لِمَنْ أَعْتَقَ”‏‏.‏ فَفَعَلَتْ عَائِشَةُ ثُمَّ قَامَ رَسُولُ اللَّهِ صَلَّى اللّٰهُ عَلَيْهِ وَسَلَّم فِي النَّاسِ، فَحَمِدَ اللَّهَ وَأَثْنَى عَلَيْهِ، ثُمَّ قَالَ ‏”‏أَمَّا بَعْدُ مَا بَالُ رِجَالٍ يَشْتَرِطُونَ شُرُوطًا لَيْسَتْ فِي كِتَابِ اللّٰه، مَا كَانَ مِنْ شَرْطٍ لَيْسَ فِي كِتَابِ اللّٰه فَهُوَ بَاطِلٌ وَإِنْ كَانَ مِائَةَ شَرْطٍ، قَضَاءُ اللَّهِ أَحَقُّ، وَشَرْطُ اللَّه أَوْثَقُ، وَإِنَّمَا الْوَلاَءُ لِمَنْ أَعْتَقَ‏”‏‏.‏

It is narrated by Hisham Bin ‘Urwah from his father, who narrated from Hazrat Aisha^ra, that she said, “Barira approached me and mentioned that she has drafted an agreement with her masters to buy her freedom. The terms were that she would pay them an uqiyyah of silver annually. She requested my assistance in this matter. I responded by suggesting, ‘If your masters are amenable, I can pay them the entire sum upfront, under the condition that the right of wala’ [allegiance or inheriting of estate] after your emancipation belongs to me.’ Barira conveyed this to her masters, but they declined the offer. When she returned, the Prophet^sa was present. She informed him about the stipulation her masters had made, insisting on retaining the right of wala’. Upon hearing this, the Prophet^sa instructed me, ‘Purchase her freedom and establish the condition that the right of wala’ belongs to you. The right of wala’ always goes to the one who emancipates.’”

“Aisha^ra did as instructed. Thereafter, Allah’s Messenger^sa addressed the people. After praising Allah, he said, ‘What is it with people who enforce conditions that are not present in the Book of Allah? Any such condition, even if they number a hundred, which does not adhere to Allah’s decrees, is null and void. The judgments of Allah are the only valid ones, and His conditions are the most steadfast. The right of wala’ always belongs to the emancipator.’”

(Sahih al-Bukhari, Kitab al-buyu‘, Bab idha ishtarata shurutan fi al-bay‘i la tahillu, Hadith 2168)