Al-Rubayyi bint Muawwidh narrated: `The Messenger of God (s) visited me the morning after my marriage was consummated. He sat on my bedding while some servant girls of ours began to play tambourine and sang eulogies of my ancestors who had died at the battle of Badr. Then one of them said: "And among us is a Prophet who knows what tomorrow brings." But he said to her: "Stop that, but say what you were saying before".' (Bukhari) .
Amir ibn Sa'd said: `Going in and finding Qaraza ibn Ka'b and Abu Mas'ud al-Ansari at a wedding where girls were singing, I said: "Is this being done in the presence of you two who are companions of God's Messenger, and were present at Badr?" They replied: "Sit down if you wish and listen along with us; or go away if you wish, for we have been given permission for amusement at a wedding."' (Nasa'i)
The actual form of weddings depends a lot on cultural backgrounds, which nowadays are often very un-Islamic in insisting on extravagance and show. The good Muslim practice is always against ostentation or waste in any form, and true Muslim weddings are happy but simple affairs. It often happens that young people have to defer marriage because they cannot afford the parties, and sometimes people demand an enormous mahr for the bride. Both practices undermine society and are un-Islamic. It is obviously important for a bride to receive a generous mahr, as an insurance policy in case of divorce and to ensure her financial independence. But this is a concession to human frailty. Hadiths recorded by Abu Daud and Tirmidhi show that the Prophet (s) forbade the giving of excessive dowries.