Imam Abu Hanifa (rahmatullahi ‘alayhi) said,
“My eyes have never fallen on anyone faster in understanding, correct in answering, and examining as Imam Malik.”
Imam al-Shafi’i (rahmatullahi ‘alayhi) said,
“Knowledge is encompassed by three people: Malik bin Anas, al-Laith bin Sa’ad and Sufyan bin ‘Uyaina.”
and
“When the scholars of knowledge are mentioned, Imam Malik is the guiding star.”
Imam Ahmad bin Hanbal (rahmatullahi ‘alayhi) said,
“I have compared Imam Malik to al-Awza’i, Hammad, al-Hakim, al-Thawri, al-Laith, in knowledge, but he is the leader in Hadith and Fiqh.”
Imam Sufyan bin ‘Uyaina (rahmatullahi ‘alayhi) said,
“May Allah have mercy upon Imam Malik. He only narrated authentic Hadith, he would never report except from the reliable. In my opinion, Madina without him, has only had a decrease in knowledge after his demise.”
Taken from: http://www.cordobaacademy.com/muwatta-of-imam-malik.html