Makhūl said: “Abraham circumcised his son Isaac at seven days of age, and Ishmael at thirteen years of age.” This was mentioned by al-Khallāl (1).

Shaykh al-Islām Ibn Taymiyyah said: “Thus, Isaac’s circumcision became an established practice among his descendants, and Ishmael’s circumcision became an established practice among his descendants” (2).

The disagreement concerning when the Prophet, peace and blessings be upon him, was circumcised has already been discussed (3).

Section
On his guidance, peace and blessings be upon him, concerning names and kunyahs (parental appellations)

It is established that he said: “The most abject name in Allah’s sight is that of a man who calls himself ‘King of Kings.’ There is no king but Allah” (4).

It is also established that he said: “The names most beloved to Allah are Abd Allāh and Abd al-Rahmān; the truest are Hārith and Hammām; and the ugliest are Harb and Murrah” (5).