1 Chronicles 6:26
As for Elkanah: the sons of Elkanah; Zophai his son, and Nahath his son,
Cross-reference
1 Chronicles 6:35
Parallel
1 Chronicles 6:35 traces Heman's ancestry through Zuph and Elkanah, while 6:26 lists Zophai and Nahath as sons of a different Elkanah. The names Zophai/Zuph may be variants.
1 Samuel 1:1
Parallel
1 Samuel 1:1 includes Zuph in Samuel's genealogy; 1 Chronicles 6:26 lists Zophai (likely the same person) as a son of Elkanah.