What is the recommendation regarding voluntary prayers that one makes up if missed?

Chapter on the Times When Prayer is Prohibited

Al-Mughni

Book of Prayer

Book 3 · Issue 5 · Bab 9

Open in Qurani

Primary text

Imam Ahmad, may Allah have mercy on him, stated that it is beloved for a person to have some voluntary prayers that he maintains, and if they are missed, he makes them up.