Sola fide is the teaching that justification is received by faith only, without any mixture of or need for good works, though in classical reformed theology, saving faith is always evidenced by good works.

Even so Abraham believed God, and it was reckoned to him as righteousness. Therefore, be sure that it is those who are of faith who are sons of Abraham. And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, "All the nations shall be blessed in you." So then those who are of faith are blessed with Abraham, the believer. For as many as are of the works of the Law are under a curse; for it is written, "Cursed is everyone who does not abide by all things written in the book of the law, to perform them." Now that no one is justified by the Law before God is evident; for, "The righteous man shall live by faith." (Galatians 3:6-11)