The seventh incarnation was Yajña, the son of Prajāpati Ruci and his wife Ākūti. He controlled the period during the change of the Svāyambhuva Manu and was assisted by demigods such as His son Yāma.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
ततः सप्तम आकूत्यां रुचेर्यज्ञोऽभ्यजायत । स यामाद्यैः सुरगणैरपात्स्वायम्भुवान्तरम्
tataḥ saptama ākūtyāṃ ruceryajño'bhyajāyata | sa yāmādyaiḥ suragaṇairapātsvāyambhuvāntaram
SB 1.3.12