Pariyāyasutta

sn46.52:16.1 Equanimity for internal things is the awakening factor of equanimity; and equanimity for external things is also the awakening factor of equanimity.

sn46.52:16.2 In this way what is concisely referred to as ‘the awakening factor of equanimity’ becomes twofold.

sn46.52:16.3 This is the way in which the seven awakening factors become fourteen.”