Imam Sufyaan once said: "Seeking out knowledge is not saying: 'So-and-so related from so-and-so; rather, seeking out knowledge is fearing Allah, the Possessor of Might and Majesty."

Source: Biography of Imam Sufyaan ath-Thawri by Salaahud-Deen ibn Ali ibn Abdul-Maujood

Muhammad ibn Zaid Al-Khunaisee reported that he heard a man say to Sufyaan Ath-Thawri: 

"Only if you would disseminate the knowledge you have with you; I would then hope that Allah would benefit some of His slaves with that knowledge and that Allah would reward you for that." Sufyaan said: "By Allah, were I to know of someone who sought out this knowledge, seeking thereby only that which is with Allah (in terms of rewards), I would, desiring that Allah should benefit him with knowledge, be the one who would go to him in his house and relate to him what I know."

“O Abu Ali (i.e. Fudayl), by Allah, we will never be able to rejoice until we take the cure of the Quran and place it over the disease of our hearts.”

Source: Biography of Imam Sufyaan ath-Thawri by Salaahud-Deen ibn Ali ibn Abdul-Maujood

In ‘Siyar A’lam an-Nubala” (7/184), Sufyaan ath-Thawri said:

ما بلغنى عن رسول الله صلى الله عليه وسلم حديث قط إلا عملت به ولو مرة

“There isn’t a single hadith of the Messenger of Allah (peace be upon him) that has reached me except that I acted upon it, even if only once.”

Imaam Sufyaan ath-Thawri said:

"Beware of doing that which will corrupt your deeds and your heart. what will corrupt your heart is sitting in the company of worldly people, greedy people, and the brothers of devils-those who spend their wealth in the disobedience of Allah."

Biography of Sufyaan Ath-Thauree, By Salaahud-Deen ibn 'Alee ibn 'Abdul-Maujood

On a particular occasion, someone wrote to Imaam Sufyaan ath-Thawri, saying, ''Advise me, but be brief." Imaam Sufyaan wrote back the following reply: "In the Name of Allah, the Most Beneficent, the Most Merciful. May Allah protect both me and you from evil. My brother, know that the grief and worries of this world do not end and that it's happiness is not lasting. So do not be remise (in your religious duties); otherwise, you will perish. And peace be upon you."

Biography of Sufyaan Ath-Thauree

By Salaahud-Deen ibn 'Alee ibn 'Abdul-Maujood

Imaam Sufyaan ath-Thawri said: 

"My brother, your religion is nothing more than your flesh and blood (you should be concerned about your religion's well-being, because if you arent, it is your flesh and blood that will pay the penalty through the punishment of Allah). Cry out of concern for your soul and have mercy on it; if you do not have mercy on it, then mercy will not be shown to it."

Biography of Sufyaan Ath-Thauree
By Salaahud-Deen ibn 'Alee ibn 'Abdul-Maujood

Abdullaah ibn Al-Mubaarak said: Sufyaan Ath-Thawri said to me:

Beware of fame. Everyone I met warned me about fame.

(As-Siyar: 7/260)