Manava Dharmashastra 7.54

7.54

maulāñ śāstravidaḥ śūrāṃl labdhalakṣān
sacivān sapta cāṣṭau vā //

Let him appoint seven or eight ministers whose ancestors have been royal servants, who are versed in the sciences, heroes skilled in the use of weapons and descended from (noble) families and who have been tried.