Shiva Purana
युगपद्वाथ संस्कारान्कुर्वीत सगणो गुरुः ॥ तत्र यत्र द्वयं वापि प्रयोगस्योपदिश्यते ॥ २१ ॥
Then the spiritual master and his associates should perform the ritualistic ceremonies simultaneously. There where either or both are indicated for use.
english translation
yugapadvAtha saMskArAnkurvIta sagaNo guruH ॥ tatra yatra dvayaM vApi prayogasyopadizyate ॥ 21 ॥
hk transliteration by Sanscript