Brihat Parashara Hora Shastra
रामकृष्णादयः सर्व ह्यवतारा भवन्ति चै। तत्रैव ते विलीयन्ते पुनः कार्योत्तर सदा॥ ९॥
did incarnate, as Ram, Krishn etc. After completing the mission, the Paramatmāńśas (of the respective) Grahas again merge (in the respective) Grahas.
english translation
rAmakRSNAdayaH sarva hyavatArA bhavanti cai। tatraiva te vilIyante punaH kAryottara sadA॥ 9॥
hk transliteration by Sanscript