The Dowry. It is permissible for the dowry to be teaching Quran, a ring of iron or anything else, a small or large amount, And it is recommended for it to be Five Hundred Dirham Sahih Muslim 1427 c
Translation
Anas b. Malik (Allah be pleased with him) reported that 'Abd al-Rahman b. 'Auf (Allah be pleased with him) married a woman for a date-stone's weight of gold and Allah's Apostle (ﷺ) said to him
Hold a wedding feast, even if only with a sheep.