The Command of Allah-azwj as in the Holy Scriptures
وَكَيْفَ يُحَكِّمُونَكَ وَعِنْدَهُمُ التَّوْرَاةُ فِيهَا حُكْمُ اللَّهِ ثُمَّ يَتَوَلَّوْنَ مِنْ بَعْدِ ذَٰلِكَ ۚ وَمَا أُولَٰئِكَ بِالْمُؤْمِنِينَ {43}
And how come they make you a judge and with them is the Torah wherein is a Judgment of Allah, then they are turning back from after that? And they are not the Momineen [5:43]
عن أبي العباس، عن أبي عبد الله (عليه السلام)، قال: «من حكم في درهمين بغير ما أنزل الله فقد كفر». قلت: كفر بما أنزل الله، أو بما نزل على محمد (صلى الله عليه و آله)؟ قال: «ويلك، إذا كفر بما انزل على محمد (صلى الله عليه و آله) [أليس] قد كفر بما أنزل الله؟
From Abu Al Abbas,
(It has been narrated) from Abu Abdullah-asws having said: ‘The one who judges regarding two Dirhams with other than what Allah-azwj has Revealed, so he has committed Kufr’. I said, ‘Kufr with what Allah-azwj Revealed, or in what was Revealed unto Muhammad-saww?’ He-asws said: ‘Woe be unto you! When he commits Kufr with what was Revealed unto Muhammad-saww, has he not committed Kufr with what Allah-azwj Revealed?’[1]
[1] تفسير العيّاشي 1: 324/ 127