Brahma Sutras
ॐ शमदमाद्युपेतः स्यात्तथाऽपि तु तद्विधेस्तदङ्गतया तेषामवश्यानुष्ठेयत्वात् ॐ ॥ ३-४-२७॥
(Even though there be no injunction about sacrifices etc.,), still one must be endowed with self-control and the like, since these are enjoined as subsidiaries of knowledge; and hence have to be practised as a matter of course.
english translation
OM zamadamAdyupetaH syAttathA'pi tu tadvidhestadaGgatayA teSAmavazyAnuSTheyatvAt OM ॥ 3-4-27॥
hk transliteration by Sanscript