As-Sam’aanee (d.562H) said in al-lnsaab (3/273): “As-Salafi: this is an ascription to the Salaf and following their ways, in that which is related from them.”

lbn al-Atheer (d.630H) said in al-Lubaab fee Tahdheebul-lnsaab (2/162), commenting upon the previous saying of as-Sam’aanee: “And a group were known by this ascription.” So the meaning is: that the term Salafi, and its ascription to them, was a matter known in the time of Imaam as-Sam’aanee, or before him.

Imaam adh-Dhahabee (d.748H) – rahimahullaah – said: “It is authentically related from ad-Daaraqutnee that he said: There is nothing more despised by me than ‘ilmul-kalaam (innovated speech and rhetorics). I say: He never entered into ‘ilmul-kalaam, nor argumentation. Rather, was a Salafee (a follower of the Salaf).” [Siyar 16/457]

Source – Statements from the Salaf on Ascription to the Salaf:
http://www.salafipublications.com/sps/sp.cfm?subsecID=SLF01&articleID=SLF010001&articlePages=1