Charak Samhita
येन नारीषु सामर्थ्यं वाजीवल्लभते [१] नरः। व्रजेच्चाभ्यधिकं येन वाजीकरणमेव तत् ॥५१॥
॥ Vajikarana॥ That process, which make a man capable of copulation with woman frequently and for a long time with stallion vigor, is called Vajikarana.
english translation
yena nArISu sAmarthyaM vAjIvallabhate [1] naraH। vrajeccAbhyadhikaM yena vAjIkaraNameva tat ॥51॥
hk transliteration by Sanscript