Shaqiq bin al-Ayzar said: I asked Ibn Umar (may Allah be pleased with them both) about payment (for going out to fight), and he said: I do not take any payment except the payment my Lord gives me. Shaqiq said: I asked Abdullah bin al-Zubayr (may Allah be pleased with them both), and he said: Leaving it is better; if you do take it, then spend it in the way of Allah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17838