These are the Graves of the Prophet Ishaq (peace be upon him) (on the right) and his wife Rifaqah (on the left), which are directly above their graves, which are underground. These tombs are on the Muslim side, along with Sarah (Peace be upon her), one of the wives of Ibrahim (Peace be upon him). The graves of Yaqub and Yusuf (peace be upon him) are on the Jewish side. Jews and Muslims are allowed to enter other places for 10 fixed days a year.
Ishaq (peace be upon him) is mentioned 17 times in the Quran.
He was born when his father Ibrahim (peace be upon him) was 100 years old, his elder brother Ismail (peace be upon him) 14 years old, and his mother Sarah (peace be upon her) 90 years. Allah mentions the joyful news of the birth of Ishaq (peace be upon him) to Ibrahim (peace be upon him) in the Qur'an in Surah Al-Saffat:
“And we gave him the joyful news of Ishaq, the Prophet, one of the righteous. And we blessed him and Ishaq. And some of their descendants are good deeds, and some are clearly wrongdoers. ” [Quran 37: verses 112-113]
Jews and Christians believe that it was Ishaq (Peace be upon him) who was prepared for the sacrifice of Ibrahim (Peace be upon him) in the al-Aqsa sanctuary in Jerusalem. The Islamic faith is that it was Ishmael (Peace be upon him) with the incident occurring in Mina, in Saudi Arabia.
According to the people of the Book, Ishaq (peace be upon him) married Rifakah (Rebekah), the daughter of Batwabil, during the life of his father. She was barren, and he prayed to Allah for the children. His prayer was heard, and she gave birth to twin boys, Al-’Ays (Esau) and Yaqoob (Jacob). The former is the parent of the Romans, while the latter, also known as Israel, is the progenitor of Banu Israil (Children of Israel).
When Ishaq (peace be upon him) grew old, he lost his sight. He died in Hebron at the age of 180.
Sources: Atlas of the Quran – Dr. Shauqi Abu Khalili, Stories of the Prophets – Ibn Kathir