A witness is required to be fair

۞ يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ كُونُوا۟ قَوَّٰمِينَ بِٱلْقِسْطِ شُهَدَآءَ لِلَّهِ وَلَوْ عَلَىٰٓ أَنفُسِكُمْ أَوِ ٱلْوَٰلِدَيْنِ وَٱلْأَقْرَبِينَ ۚ إِن يَكُنْ غَنِيًّا أَوْ فَقِيرًۭا فَٱللَّهُ أَوْلَىٰ بِهِمَا ۖ فَلَا تَتَّبِعُوا۟ ٱلْهَوَىٰٓ أَن تَعْدِلُوا۟ ۚ وَإِن تَلْوُۥٓا۟ أَوْ تُعْرِضُوا۟ فَإِنَّ ٱللَّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًۭا

O ye who believe! stand out firmly for justice, as witnesses to Allah, even as against yourselves, or your parents, or your kin, and whether it be (against) rich or poor: for Allah can best protect both. Follow not the lusts (of your hearts), lest ye swerve, and if ye distort (justice) or decline to do justice, verily Allah is well-acquainted with all that ye do.

يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ شَهَٰدَةُ بَيْنِكُمْ إِذَا حَضَرَ أَحَدَكُمُ ٱلْمَوْتُ حِينَ ٱلْوَصِيَّةِ ٱثْنَانِ ذَوَا عَدْلٍۢ مِّنكُمْ أَوْ ءَاخَرَانِ مِنْ غَيْرِكُمْ إِنْ أَنتُمْ ضَرَبْتُمْ فِى ٱلْأَرْضِ فَأَصَٰبَتْكُم مُّصِيبَةُ ٱلْمَوْتِ ۚ تَحْبِسُونَهُمَا مِنۢ بَعْدِ ٱلصَّلَوٰةِ فَيُقْسِمَانِ بِٱللَّهِ إِنِ ٱرْتَبْتُمْ لَا نَشْتَرِى بِهِۦ ثَمَنًۭا وَلَوْ كَانَ ذَا قُرْبَىٰ ۙ وَلَا نَكْتُمُ شَهَٰدَةَ ٱللَّهِ إِنَّآ إِذًۭا لَّمِنَ ٱلْءَاثِمِينَ

O ye who believe! When death approaches any of you, (take) witnesses among yourselves when making bequests,- two just men of your own (brotherhood) or others from outside if ye are journeying through the earth, and the chance of death befalls you (thus). If ye doubt (their truth), detain them both after prayer, and let them both swear by Allah: "We wish not in this for any worldly gain, even though the (beneficiary) be our near relation: we shall hide not the evidence before Allah: if we do, then behold! the sin be upon us!"

فَإِذَا بَلَغْنَ أَجَلَهُنَّ فَأَمْسِكُوهُنَّ بِمَعْرُوفٍ أَوْ فَارِقُوهُنَّ بِمَعْرُوفٍۢ وَأَشْهِدُوا۟ ذَوَىْ عَدْلٍۢ مِّنكُمْ وَأَقِيمُوا۟ ٱلشَّهَٰدَةَ لِلَّهِ ۚ ذَٰلِكُمْ يُوعَظُ بِهِۦ مَن كَانَ يُؤْمِنُ بِٱللَّهِ وَٱلْيَوْمِ ٱلْءَاخِرِ ۚ وَمَن يَتَّقِ ٱللَّهَ يَجْعَل لَّهُۥ مَخْرَجًۭا

Thus when they fulfil their term appointed, either take them back on equitable terms or part with them on equitable terms; and take for witness two persons from among you, endued with justice, and establish the evidence (as) before Allah. Such is the admonition given to him who believes in Allah and the Last Day. And for those who fear Allah, He (ever) prepares a way out,