Easton's Bible Dictionary (1897)
Noble, probably a tribe descended from one of the sons of Ishmael, with whom the trans-Jordanic tribes made war (1 Chr. 5:19).
Smith's Bible Dictionary (1863)
(nobility), the name of an Arab tribe mentioned only in (1 Chronicles 6:19) in the account of the war of the Reubenites against the Hagarites. vs. 9-22. It is probable that Nodab, their ancestor, was the son of Ishmael, being mentioned with two of his other sons in the passage above cited, and was therefore a grandson of Abraham.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
NO'DAB (nobility), an Arab tribe against which the trans-Jordanic tribes waged war. 1 Chr 6:19. The other names associated with Nodab - Hagar Jetur, and Nephish - were sons of Ishmael, 1 Chr 1:31, which seems to point to Nodab's descent from Ishmael also.
Hitchcock's Bible Names (1869)
vowing of his own accord