Allah Almighty says: "There is no sin upon you if you divorce women while you have not touched them nor fixed for them a dowry. But give them provision (in that case): the wealthy according to his means and the one in straitened circumstances according to his means, a provision according to what is customary, an obligation upon the doers of good." [Surah al-Baqarah: 236]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصداق / Q14405