Brihat Parashara Hora Shastra
धनेशे कर्मभावस्थे वसुसङ्ख्यास्तु सूनवः । पञ्चमात् पञ्चमे मन्दे सुतस्थे च तदीश्वरे ॥ २७॥
Śani in Dharm Bhava, while Putr‟s Lord is in Putr itself, gives 7 sons, out of which twins will be born twice.
english translation
dhaneze karmabhAvasthe vasusaGkhyAstu sUnavaH । paJcamAt paJcame mande sutasthe ca tadIzvare ॥ 27॥
hk transliteration by Sanscript