VASHNI (văsh'nī, Heb. washnî, weak). The name of the firstborn of Samuel, according to 1Chr.6.28 (kjv). This presents a problem, since another passage says that Samuel’s firstborn was Joel and his second Abijah (1Sam.8.2). The Hebrew text seems to be corrupt, and perhaps washnî should be translated “and the second” (so niv), the name of the first son being accidentally omitted by some copyist.

VASHNI văsh’ nī (וַשְׁנִ֖י, LXXB Σανει, LXXA Σανι). Samuel’s first-born son, according to KJV (1 Chron 6:28). However, since 1 Samuel 8:2 and Lagarde’s Gr. OT and Syr. of 1 Chronicles 6:28 all list Joel as Samuel’s firstborn, most textual scholars believe his name dropped out of the MT due to homoioteleuton. They restore it, and by adding the definite article and repointing the word “Vashni” they obtain the tr. “and the second” (so Lagarde Gr. OT, Syr., ASV, RSV).

International Standard Bible Encyclopedia (1915)

Read in 1Ch 6:28 the King James Version (Hebrew 13) as the name of the firstborn son of Samuel. According to 1Ch 6:33 (Hebrew 18) and 1Sa 8:2, Samuel’s oldest son was Joel, and the second Abijah. The explanation of this is that in 1Ch 6:28 the word taken then as a proper name is really "and second"; so following Septuagint, Lucian, and Syriac we read (as the Revised Version (British and American)), "And the sons of Samuel: the first-born, Joel, and the second Abijah."