From Shihaab Ibn Khiraash  who said: ’Umar Ibn ’Abdul-’Azeez (d.101H) – rahimahullaah – wrote to a man,
“May peace be upon you, to proceed:
So verily I advise you to fear Allaah, and to make His Command the objective, and to follow the Sunnah of His Messenger, and to leave off what people invented after him (sallallaahu ’alayhi wa sallam), from whatever is confirmed as his Sunnah, and his supply will suffice you.
Then know that there cannot ever be any innovation, except that a proof against it has already passed, and there is a warning in it. So adhere strictly to the Sunnah, for verily the Sunnah is – with the permission of Allaah – a protection for you. Verily the one who practices the Sunnah is one who indeed knows what opposes it from mistakes and error, and foolishness, and deep thorough study.
So be pleased with for yourself what the people (i.e. the Salafus-Saalih) were pleased with for themselves, for verily they stopped upon knowledge, and they sufficed with penetrating insight, and they were the strongest in studying the matters, and the virtue that was in them, in that case, they were the most adequate; since they (the Salafus-Saalih – Righteous Predecessors) have already preceded. So indeed the guidance is not what you are upon, rather they preceded you to it. Therefore you say, he innovated a newly invented matter after them, so no one invents something, except that he opposes their path, and considers himself to be better than them. Indeed whatever they spoke was sufficient, and whatever they described was satisfying. So whatever is below them is deficient, and there is no good above them. Indeed people fell short of their mark, so they became dull, and others were too ambitious, so they went into extremes, and verily they (the Salaf) were in between the two, so they were upon the straight guidance.”
 He is Shihaab Ibn Khiraash Ibn Hawshab ash-Shaybaanee, from Koofah. He moved to Shaam, and lived in ar-Ramlah inside of Palestine, and he died there. He was sadooq (truthful), a person of the Sunnah. Refer to Tahdheebul-Kamaal (12/568-572).
 Related by Ibn Battah in al-Ibaanah (1/321-322), and by al-Laalikaa‘ee in Sharh Usoolul-I’tiqaad (no. 16)