Mudgalapurana 2.31.2

2.31.2

yadarthe gaṇarājo'yaṃ muniputro'bhavatprabho |
tanna mudgala sāmānyaṃ dhanyaṃ janmāsurasya ca ||

for whose sake this Gaṇarāja became the sage's son, O Lord. / That is no ordinary matter, O Mudgala, and blessed is the birth of the asura.