The Quran

۞ قُل إِنَّما أَعِظُكُم بِواحِدَةٍ ۖ أَن تَقوموا لِلَّهِ مَثنىٰ وَفُرادىٰ ثُمَّ تَتَفَكَّروا ۚ ما بِصاحِبِكُم مِن جِنَّةٍ ۚ إِن هُوَ إِلّا نَذيرٌ لَكُم بَينَ يَدَي عَذابٍ شَديدٍ

Muhammad Asad

Say: "I counsel you one thing only: Be [everconscious of] standing before God, whether you are in the company of others or alone;¹ and then bethink yourselves [that] there is no madness in [this prophet,] your fellow-man:² he is only a warner to you of suffering severe to come."

Lit., "two by two (mathna) and singly (furada)". According to Razi, the expression mathna denotes, in this context, "together with another person" or "other persons": hence, the above phrase may be understood to refer to man's social behaviour - i.e., his actions concerning others - as well as to his inner, personal attitude in all situations requiring a moral choice.
See note 150 on 7:184.