Al-Kāfi - Volume 7 > The Witness for the Will
Hadith #4

4- مُحَمَّدُ بْنُ إِسْمَاعِيلَ عَنِ الْفَضْلِ بْنِ شَاذَانَ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ رِبْعِيٍّ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) فِي شَهَادَةِ امْرَأَةٍ حَضَرَتْ رَجُلا يُوصِي لَيْسَ مَعَهَا رَجُلٌ فَقَالَ يُجَازُ رُبُعُ مَا أَوْصَى بِحِسَابِ شَهَادَتِهَا.

4. Muhammad ibn ’Isma‘il has narrated from al-Fadl ibn Shadhan, from ibn abu ‘Umayr from Rib‘iy who has narrated the following: “I once asked abu ‘Abd Allah, ‘Alayhi al-Salam, if a woman’s bearing witness to the will of a man when no man is available is accepted. He (the Imam) said, ‘It is effective for one-fourth of what is willed according to her testimony.’”