Isa bin Abdullah narrated from his father, from his grandfather, that two women came to Sayyiduna Ali (may Allah be pleased with him) asking him (for help): one was an Arab woman and the other was her freedwoman. Sayyiduna Ali (may Allah be pleased with him) ordered for each of them a kurr (a measure) of food and forty dirhams. The freedwoman took what she was given and left. The Arab woman said: O Commander of the Believers, do you give me the same as you gave her, when I am an Arab and she is a freedwoman? Sayyiduna Ali (may Allah be pleased with him) said to her: I have looked into the Book of Allah, and I did not see in it any superiority for the descendants of Isma'il over the descendants of Ishaq.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12990