Abd al-Khabir bin Thabit bin Qays bin Shammas narrates from his father, who narrates from his grandfather, that a woman called Umm Khallad (may Allah be pleased with her) came to the Prophet (peace and blessings be upon him) veiled, asking about her son who had been martyred. Some of the Companions (may Allah be pleased with them) said: "She is asking the Prophet (peace and blessings be upon him) about her son while veiled?" The woman said: "My son has been killed; has my modesty come to an end as well?" He (peace and blessings be upon him) said: "Your son will receive the reward of two martyrs." The woman said: "O Messenger of Allah (peace and blessings be upon him)! Why is that?" He (peace and blessings be upon him) said: "Because the People of the Book killed him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18591