In the whole lineage of the Holy Prophet (sallallahu alaihi wa sallam), each and every person is not only free of Shirk and Kufr, but instead they were very beloved to Almighty Allah with fine characters and superior qualities and attributes.
As is mentioned in the Hadith that the Holy Prophet (Sallallahu alaihi wa sallam) said:
I have come through Nikah (marriage) and not through any unlawful relations. (Sunan Kubra Lil Baihaqui, Vol. 10, Pg. No. 454; Seerat Halbiya, Vol. 1 ,Pg. No. 33, Khasais Kubra, Vol. 1, Pg. No. 37)
From the birth of Hadhrat Adam (peace be upon him) to my birth, nothing from the era of ignorance has touched me and Allah Ta'ala says:
Allah Ta'ala says:
O Prophet! We kept transferring your Noor into worshippers.
Surah Ash-Ashu'ara-219
The Mufassirin (exegetes of the Holy Quran) have said that it means that Holy Prophet (Sallallahu alaihi wa sallam) has been passed on through pure personages.
ِThere is a Tradition in Abu Naeem that the Holy Prophet has been passed on from one Prophet to another Prophet until He (Sallallahu alaihi wa sallam) was born from the womb of His mother.
In the lineage of the Holy Prophet (Sallallahu alaihi wa sallam), all the ancestors are superior to the ancestors of everyone else. As is mentioned in the Hadith of Tabarani and Baihaqui:
Translation of Hadith: Ummul Momineen Hadhrat Aisha Siddiqua (May Allah be well pleased with her) says: Jibrail (peace be upon him) says: I have seen the whole east and the west and couldn't find anyone better than the Holy Prophet (sallallahu alaihi wa sallam) and any family more distinguished than Bani Hashim.
The great ancestors of the Holy Prophet (sallallahu alaihi wa sallam), Hadhrat Ibrahim (peace be upon him) had two sons – (1) Hadhrat Ismail (peace be upon him) (2) Hadhrat Ishaaq (peace be upon him)
Hadhrat Ishaaq (peace be upon Him) had a son whose names are Hadhrat Israil and Hadhrat Yaqoob (peace be upon him). That's the reason his progeny is called Bani Israil, lit. the people of Israel.
Before Hadhrat Isa (Peace be upon him), all the Prophets were from Hadhrat Yaqoob's progeny. The Holy Prophet (Sallallahu alaihi wa sallam) belongs to the relations of Hadhrat Ismail. The Holy Prophet (sallallahu alaihi wa sallam) is a descendent of the Hadhrat Ismail (peace be upon him). In his progeny, excepting the Holy Prophet (Sallallahu alaihi wa sallam), no other Prophet has come into this world. His Noor has been passed on from person to person. Almost 570 years after Hadhrat Isa (peace be upon him), the Holy Prophet (Sallallahu alaihi wa sallam) graced the world with His presence.