妙法蓮華經玄贊 1.105

1.105

梵云摩訶俱瑟恥羅，此云大膝膝蓋故，俱絺羅訛也。此舍利弗舅氏，因共佛論悟解得果，如律中說。

In Sanskrit it is Mahākauṣṭhila; here it is translated as 'Great Knee' due to the kneecap. 'Juxiluo' is corrupted. He was Śāriputra's maternal uncle; he awakened and attained the fruit through debating with the Buddha, as recounted in the Vinaya.