SB 4.1.40

ūrjāyāṁ jajñire putrā
 vasiṣṭhasya parantapa
citraketu-pradhānās te
 sapta brahmarṣayo ’malāḥ
Word for word: 
ūrjāyām — in Ūrjā; jajñire — took birth; putrāḥ — sons; vasiṣṭhasya — of the great sage Vasiṣṭha; parantapa — O great one; citraketu — Citraketu; pradhānāḥ — headed by; te — all the sons; sapta — seven; brahma-ṛṣayaḥ — great sages with spiritual knowledge; amalāḥ — without contamination.
Translation: 
The great sage Vasiṣṭha begot in his wife, Ūrjā [sometimes called Arundhatī], seven spotlessly great sages, headed by the sage named Citraketu.