إنْif كنتَyou are فيamong قُعدُدِthose nearest in descent أبنائهِhis descendants
إنْ كنتَ في قُعدُدِ أبنائهِ
فقدthen indeed سقَىhe watered أمَّكَyour mother منwith some of مائهِhis water (semen)
فقد سقَى أمَّكَ من مائهِ
If you are among his nearest descendants,
then he has watered your mother with his water.
Sol 6.1