MEBUNNAI (mē-bŭn'ī, Heb. mevunnay, well-built). One of David’s bodyguards (2Sam.23.27) who killed a Philistine giant (2Sam.21.18, Sibbecai). Due to a scribal error the spelling of this name is quite varied.

MEBUNNAI mĭ bŭn’ ī (מְבֻנַּ֖י). One of David’s thirty mighty men (2 Sam 23:27); called Sibbecai in 1 Chronicles 11:29; 27:11.

International Standard Bible Encyclopedia (1915)

me-bun’-i, me-bun’-a-i (mebhunnay, "well-built"): One of David’s "braves" (2Sa 23:27). In 2Sa 21:18 he is named "Sibbechai" (the Revised Version (British and American) "Sibbecai"), and is there mentioned as the slayer of a Philistine giant. The Revised Version (British and American) spelling occurs in 1Ch 11:29, the King James Version "Sibbechai" in 1Ch 20:4 (compare 2Sa 21:18); and in 1Ch 27:11 the Revised Version (British and American) spelling recurs, where this person is mentioned as captain of the 8th course of the 12 monthly courses that served the king in rota. Scribal error, and the similarity in Hebrew spelling of the two forms accounts for the difference in spelling. the Revised Version (British and American) consistently tries to keep this right.