You touch a spirit called by you with a summoning spell and establish a magical bond with it.

You extend the duration of the spirit manifestation to concentration, up to 24 hours. You can affect only one spirit at time and if it is ever more than 1 mile from you at the end of your turn, the spell ends and the spirit disappears. This spell allows you to maintain concentration on the summoning spell even while sleeping, casting spells as rituals or casting spells with a long casting time. If you do so, your spirit manifestation falls into an inactive, motionless state which renders it unconscious for the time.

At Higher Levels. When you cast this spell using a spell slot of a higher level, the duration increases to 10 days with a 6th-level slot, to 30 days with a 7th- level slot, to 180 days with an 8th-level slot, and to a year and a day with a 9th-level spell slot. However it still requires maintaining concentration on the summoning spell.