Shiva Purana
माहेश्वरास्समाख्याता कर्मयज्ञरता भुवि ॥ तस्मादाभ्यन्तरे कुर्युः शैवा माहेश्वरा वहिः ॥ १० ॥
On this earth the gods of Maheśvara are described as engaged in ritualistic sacrifices Therefore the Shivas and Maheshwaras should be placed inside and outside.
english translation
mAhezvarAssamAkhyAtA karmayajJaratA bhuvi ॥ tasmAdAbhyantare kuryuH zaivA mAhezvarA vahiH ॥ 10 ॥
hk transliteration by Sanscript