Al-Kāfi - Volume 7 > The Witness for the Will
Hadith #3

3- مُحَمَّدُ بْنُ إِسْمَاعِيلَ عَنِ الْفَضْلِ بْنِ شَاذَانَ وَعَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ جَمِيعاً عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ هِشَامِ بْنِ الْحَكَمِ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) فِي قَوْلِ اللهِ تَبَارَكَ وَتَعَالَى أَوْ آخَرانِ مِنْ غَيْرِكُمْ قَالَ إِذَا كَانَ الرَّجُلُ فِي بَلَدٍ لَيْسَ فِيهِ مُسْلِمٌ جَازَتْ شَهَادَةُ مَنْ لَيْسَ بِمُسْلِمٍ عَلَى الْوَصِيَّةِ.

3. Muhammad ibn ’Isma‘il has narrated from al-Fadl ibn Shadhan and Ali ibn Ibrahim has narrated from his father from all from ibn abu ‘Umayr from Fiisham ibn al-Hakam who has narrated the following: “About the meaning of the words of Allah, most Majestic, most Glorious, ‘. . . and two people from others who are not of your people’ abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘This applies when he is in a place where Muslims are not available, then asking a non-Muslim to bear witness to a will is permissible.’”