Assalaamu alaykum, Shaykh. Is the belief that Allah has a son (as Christians claim) or a daughter (as the tribe of Quraysh believed) Shirk (associating partners with Allah) in Ruboobiyyah (Lordship) or Shirk in Asmaa wa Sifaat (Divine Names and Attributes)? Please do not refer to other fatwas.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.

Believing that Allah, the Exalted, has a son involves Shirk in Asmaa wa Sifaat (Allah's Names and Attributes) and Shirk in Ruboobiyyah (Allah's Lordship), and it leads to Shirk in Uloohiyyah (the Servitude to Allah); thus incorporating the three categories of Shirk.

Shaykh Ibn ʻUthaymeen said, "Shirk means associating partners to Allah in His Ruboobiyyah or His Uloohiyyah or His Asmaa wa Sifaat. Shirk in Ruboobiyyah means believing that there is another creator of the universe beside Allah or believe in an assistant to Him in the creation ... Shirk in Asmaa wa Sifaat means believing that the created beings possess attributes similar to the divine Attributes of the Creator." [Fataawa ʻala Ad-Darb]

Dr. ʻAbdul-ʻAzeez ibn Muhammad Aal Abdul-Lateef said, "Shirk in Ruboobiyyah accompanies Shirk in Asmaa wa Sifaat and inevitably leads to Shirk Uloohiyyah..." [Inhiraafaat Al-Qubooriyyeen: Ad-Daa' wa Ad-Dawaa']

Allah knows best.