For the final s and for the ṣ of sasajuṣ is substituted ru , at the end of a word.,
Thus अग्निरत्र, वायुरत्र ॥ So also सजूर्ऋषिभिः, सजूर्देवेभिः ॥ सजुष् is derived from जुष् with the affix क्विप् and the preposition सह, which is changed to स in Bahuvrihi. The lengthening takes place by 8.2.76. and the word means सप्रीतिः ॥ The रु is र्, but it should be distinguished from it. This secondary र् (or रु) undergoes a distinct and separate Sandhi change from that of the primary र् ॥,