As-salaamu'alaykum,
In a speech he delivered from the pulpit, Umar ibn Al-Khattab said,
"Lo! Verily, the people of opinion (those who place their opinions on an equal footing with the Qur'an and Sunnah) are the enemies of the Sunnah practices of the Prophet (sallallahu alayhi wa sallam). Not being able to memorise hadeeth narrations, they issue legal rulings based on their opinions. Consequently, they not only go astray themselves, but also lead others astray. Lo! Indeed, instead of expressing our opinions, we follow (the Prophet's example); and instead of innovating, we abide by (the Prophet's teachings). We will not go astray as long as we adhere to what has (authentically) been related to us (from the Prophet)."
'Amr ibn Maymoon related from his father that a man once went to Umar ibn al-Khattab and said,
"O Leader of the Believers, when we conquered Al-Madaain, we found a book that contained in it beautiful speech."
Umar asked,
"Was that speech from the Book of Allah?"
The man replied,
"No."
Umar asked someone to hand him a stick, after which he proceeded to beat the man, and all the while he was reciting the saying of Allah:
Alif, Lam, Ra. These are the verses of the clear Book.
Indeed, We have sent it down as an Arabic Qur'an that you might understand.
We relate to you, [O Muhammad], the best of stories in what We have revealed to you of this Qur'an although you were, before it, among the unaware.
(Qur'an, 12: 1-3)
Umar then said,
"Verily, what destroyed those who came before you was the fact that they betook themselves to the books of their scholars and priests, while they abandoned the Torah and the Injeel (the Gospel). And they continued to do that until the Torah and the Injeel became obliterated (from their collective memories), and the knowledge that they contained (simply) went away."
(Because its chain is disconnected, this narration is somewhat weak; however, there are other chains that strengthen it. Refer to Manaaqib Umar, by Ibn al-Jawzi, pg. 23)
In a speech he delivered from the pulpit, Umar ibn Al-Khattab said,
"Lo! Verily, the people of opinion (those who place their opinions on an equal footing with the Qur'an and Sunnah) are the enemies of the Sunnah practices of the Prophet (sallallahu alayhi wa sallam). Not being able to memorise hadeeth narrations, they issue legal rulings based on their opinions. Consequently, they not only go astray themselves, but also lead others astray. Lo! Indeed, instead of expressing our opinions, we follow (the Prophet's example); and instead of innovating, we abide by (the Prophet's teachings). We will not go astray as long as we adhere to what has (authentically) been related to us (from the Prophet)."
'Amr ibn Maymoon related from his father that a man once went to Umar ibn al-Khattab and said,
"O Leader of the Believers, when we conquered Al-Madaain, we found a book that contained in it beautiful speech."
Umar asked,
"Was that speech from the Book of Allah?"
The man replied,
"No."
Umar asked someone to hand him a stick, after which he proceeded to beat the man, and all the while he was reciting the saying of Allah:
Alif, Lam, Ra. These are the verses of the clear Book.
Indeed, We have sent it down as an Arabic Qur'an that you might understand.
We relate to you, [O Muhammad], the best of stories in what We have revealed to you of this Qur'an although you were, before it, among the unaware.
(Qur'an, 12: 1-3)
Umar then said,
"Verily, what destroyed those who came before you was the fact that they betook themselves to the books of their scholars and priests, while they abandoned the Torah and the Injeel (the Gospel). And they continued to do that until the Torah and the Injeel became obliterated (from their collective memories), and the knowledge that they contained (simply) went away."
(Because its chain is disconnected, this narration is somewhat weak; however, there are other chains that strengthen it. Refer to Manaaqib Umar, by Ibn al-Jawzi, pg. 23)