Qays bin Abi Hazim and Amir al-Sha'bi (may Allah have mercy on them) said that Marwan said to Sayyiduna Ayman bin Khuraym (may Allah be pleased with him): "Why do you not join us and fight?" He replied: "My father and my paternal uncle, who took part in Badr (may Allah be pleased with them both), took a pledge from me that I would never fight against anyone who recites the testimony of faith. If you give me a guarantee that you will save me from Hell, then I will fight alongside you." Marwan said: "Get out of here." So he left, saying:
I cannot fight anyone who prays;
His is the kingship, and mine would be the sin.
Shall I kill a Muslim without any crime,
For the sake of a ruler, when the other one too is from Quraysh?
I seek refuge in Allah from such ignorance and frenzy;
It would be of no benefit to me my whole life long.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16811