Shiva Purana
श्रुतेरध्ययनात्पुण्यं यदाप्नोति द्विजोत्तमः ॥ तदध्यापनतश्चापि द्विगुणं फलमश्नुते ॥ २ ॥
By teaching the Veda, an excellent brahmin attains twice the merit that he attains by studying it.
english translation
zruteradhyayanAtpuNyaM yadApnoti dvijottamaH ॥ tadadhyApanatazcApi dviguNaM phalamaznute ॥ 2 ॥
hk transliteration by Sanscript