Tafsir of Al-Ma'idah 5:111

(And when I inspired the disciples) meaning: I commanded them through the Gospel by your tongue, or I commanded them by the tongues of My messengers. The usage of "inspiration" (wahy) to mean "command" exists in the speech of the Arabs, as al-Zajjaj said, citing the poem: "Praise be to Allah, by whose permission the heaven stood firm and became tranquil; He inspired (awha) it to settle, and so it settled," meaning He commanded it to settle, and it obeyed. It is also said: the intent of the inspiration to them is God Almighty’s act of inspiring them—as in His saying: "And your Lord inspired the bee," and "We inspired the mother of Moses." This is narrated from al-Suddi and Qatada. The reason why the word "inspiration" was not left to its literal sense is because it is specific to the prophets (peace be upon them), and the disciples were not such. The meaning of "disciples" has preceded, as has the explanation that His saying (Exalted is He) (that you believe in Me and My messenger) is an explication of the meaning of "speech" contained within the inspiration. It is also said that it is an infinitive particle (masdariyyah), meaning: "by believing in..." and the discussion regarding its usage with imperatives has preceded. The mention of the title of "messenger" is to draw attention to the nature of believing in him (peace be upon him) and to signal that he (peace be upon him) is not to be removed from his bounds, whether by degradation or elevation.

(They said: "We have believed") in accordance with what we were commanded, (and bear witness that we are Muslims), meaning: sincere in our faith, or obedient to that which we have been commanded.