Dual (adverbially) of sheba'; seven- times -- seven(-fold, times).
see HEBREW sheba'
H7659. shibathayim
שִׁבְעָתַ֫יִם noun feminine dual seven-fold, seven times (compare Ges§§ 97h, 134r); —
1 seven-fold, seven times as much, Isaiah 30:26; Proverbs 6:31; as adverb Genesis 4:15, 24; Psalm 79:12.
2 seven times, adverb Psalm 12:7. — 2 Samuel 21:9 read Qr שְׁבַעְתָּם see I. שֶׁבַע.