The Scofield Bible Commentary, by Cyrus Ingerson Scofield, [1917], at sacred-texts.com
Nehiloth
Nehiloth is not a musical instrument, but means "inheritance," and indicates the character of the Psalm. The righteous are the Lord's inheritance.
fear
(See Scofield) - (Psa 19:9).
trust
(See Scofield) - (Psa 2:12).