Sa’d bin ‘Abd Qays R was from Banu (Family of) Zarib bin Harith.
His ancestor Harith was a son of Fihr.

Fihr was the first person to be called Quraysh.
The Quraysh tribe started from Fihr. He was the ancestor of all Quraysh.
Muhammad  S was also a descendent of Quraysh.

Fihr was a descendent of Isma’il A (Ishmael).

Isma’il A (Ishmael) was son of Ibrahim A (Abraham) and Hajar (Hagar).

Ibrahim A (Abraham) constructed Ka’bah in Makkah as a place to worship Allah (God).

His son Isma’il A (Ishmael) helped him in the construction of Ka’bah.

Isma’il A (Ishmael) and Ibrahim A (Abraham) were both Rusul (Messengers) of Allah (God).

Muhammad S was the last Rasul (Messenger) of Allah.

Muhammad S was selected as a Rasul (Messenger) in the year 14BH (Before Hijrah) (608 AD).

For the first three years, Muslims did not declare their Islam.

Quraysh turned hostile, as soon as Muhammad S declared Islam.
Islam was declared publicly in the year 10BH (Before Hijrah) (612 AD).

Quraysh did not want to see Islam attracting more followers. They were afraid that Quraysh might loose their leadership position in Arabia.

Quraysh were the guardians of Ka’bah. They were the spiritual leadership of Arabs. Islam had changed all of the existing social and religious equations.

The Quraysh decide to stop Islam, before its growth. They used to ridicule, harass and torture Muslims.

Many Muslims could not tolerate the torture. In the year 9BH (Before Hijrah) (613 AD), Muhammad S allowed the early Muslims to migrate out of Makkah.

More than one hundred (100) Muslims migrated to Habash (Ethiopia), at different times in small groups, to save themselves from the torture of Quraysh. The Christian King Najjashi (Negus) of Habash (Ethiopia) welcomed the migrants Muslims.

Sa’d bin ‘Abd Qays R had a brother named Harith bin ‘Abd Qays R. Both of them were among the as-Sabiqin al-Awwalin (Early converts to Islam).

Both Sa’d bin ‘Abd Qays R and his brother named Harith bin ‘Abd Qays R migrated to Habash (Ethiopia).