Brihat Parashara Hora Shastra
लग्नाद् भाग्यगते जीवे जीवाद् भाग्यगते भृगौ । लग्नेशे भृगुयुक्ते वा चत्वारिंशे सुतं वदेत् ॥ २०॥
If Guru is in Dharm Bhava, while Śukr is in the 9th from Guru along with Lagn‟s Lord, one will beget a child at the age of 40.
english translation
lagnAd bhAgyagate jIve jIvAd bhAgyagate bhRgau । lagneze bhRguyukte vA catvAriMze sutaM vadet ॥ 20॥
hk transliteration by Sanscript