Yāska's Nirukta 2.13

2.13

sādhāranāny uttarāni so divaś ca ādityasya ca/
yāni tv asya prādhānyena uparistāt tāni vyākhyāsyāmah/
ādityaḥ kasmād,.ādatte rasān,.ādatte bhāṣam jyotiṣām,.ādīpto bhāṣā iti vā aditeḥ putra iti vā/
alpa prayogam tv asya etad ārca abhyāmnāye sūkta bhāk.''.sūryam āditeyam''.aditeḥ putram/
evam anyāsām api devatānām āditya pravādāḥ stutayo bhavanti tad yathā etat mitrasya varuṇasya aryaman6.dakṣasya bhagasya aṃśasya iti/
atha api mitrā varuṇayoh/''.ādityā dānunaspatī''.dānapatī/
atha api mitrasya ekasya/''.pra samitra marto astu prayasvān yas ta āditya śikṣati vratena''.ity api nigamo bhavati/
atha api varuṇasya ekasya.''.athā vayam āditya vrate tava/
vratam iti karma nāma nivṛtti karma vārayati iti satah,.idam api itarad vratam etasmād eva vṛṇoti iti satas,.annam api vratam ucyate yad āvṛṇoti śarīram/