Brihat Parashara Hora Shastra
लग्नजायास्थितैः सौम्यैः पापाख्यैः खाऽम्बुसंस्थितैः । योगो वज्राभिधः प्रोक्तः वीपरीतस्थितैर्यवः ॥ ११॥
Vajr Yog is caused by all benefics in Lagn and Yuvati Bhava, or all malefics in Bandhu and Karm Bhava. In a contrary situation, i.e. all benefics in Bandhu and Karm Bhava, or all malefics in Lagn and Yuvati Bhava, Yav Yog is generated.
english translation
lagnajAyAsthitaiH saumyaiH pApAkhyaiH khA'mbusaMsthitaiH । yogo vajrAbhidhaH proktaH vIparItasthitairyavaH ॥ 11॥
hk transliteration by Sanscript