The Quran

كَيفَ يَكونُ لِلمُشرِكينَ عَهدٌ عِندَ اللَّهِ وَعِندَ رَسولِهِ إِلَّا الَّذينَ عاهَدتُم عِندَ المَسجِدِ الحَرامِ ۖ فَمَا استَقاموا لَكُم فَاستَقيموا لَهُم ۚ إِنَّ اللَّهَ يُحِبُّ المُتَّقينَ

Muhammad Asad

HOW COULD they who ascribe divinity to aught beside God be granted a covenant by God and His Apostle,¹ unless it be those [of them] with whom you [O believers] have made a covenant in the vicinity of the Inviolable House of Worship?² [As for the latter,] so long as they remain true to you, be true to them: for, verily, God loves those who are conscious of Him.

Lit., "have a covenant before [or "in the sight of"] God and His Apostle": i.e., be protected by those who believe in God and His Apostle. The specific reference to the latter is meant to stress the fact that he speaks and acts in the name of God.
Cf. verse 4 above. The "covenant" alluded to is the truce-agreement concluded in 6 H. at Hudaybiyyah, in the vicinity of Mecca, between the Prophet and the pagan Quraysh, which was (and was obviously intended to remain) a model of the self-restraint and the tolerance expected of true believers with regard to such of the unbelievers as are not openly hostile to them.