Brihat Parashara Hora Shastra
तत्रापि चार्गला ज्ञेया विपरीता द्विजोत्तम । तथापि खेटभावानां फलमर्गलितं विदुः ॥ ५॥
If there are 3, or more malefics in the 3rd they will cause Vipreet Argala (more effective intervention), which will also be harmless and be very favourable.
english translation
tatrApi cArgalA jJeyA viparItA dvijottama । tathApi kheTabhAvAnAM phalamargalitaM viduH ॥ 5॥
hk transliteration by Sanscript