The nikah is the marriage contract, the religious ceremony that makes a Muslim marriage official, and for a first-time guest it can feel like a quietly serious event you don't want to get wrong. The reassuring truth is that it's short, welcoming, and there's very little a guest is expected to do beyond be present.
Here's what happens, so you can relax and follow along.
What the nikah is
The nikah is the contract at the heart of the wedding, usually performed by an imam or a respected elder, often at the mosque or the venue, and sometimes in the days before the larger celebration. The essentials are the same across communities: the couple's consent, the presence of witnesses, and the mahr.
The walima, the banquet that follows, is the celebration most guests attend. The nikah itself is usually the smaller, more formal part.
The mahr, in plain terms
The mahr is a sum or gift, money, jewellery or something else of value, that the groom gives the bride as part of the contract. It belongs to her alone, it's agreed between them before the ceremony, and it can be given then or promised for later. It's a right the bride holds, not a price, and guests don't contribute to it.
The witnesses and the structure
The ceremony needs at least two adult Muslim witnesses, and the consent of both parties is asked and given aloud. The imam may give a short sermon, the contract is recited and signed, and the mahr is confirmed. The whole thing is often over in well under an hour, followed by a dua, a prayer, for the couple.
If the bride has a wali, a male guardian, his presence and agreement may be part of the ceremony in many traditions, though practices vary by community.
What to wear and expect
Dress modestly and respectfully, covered shoulders and knees as a baseline, and a headscarf for women if the ceremony is in a mosque. Shoes come off at the mosque entrance. There may be separate seating or separate rooms for men and women, and there will be no alcohol. None of it is complicated, it's just useful to know before you arrive.
The gift
Gifts are usually given at the walima rather than the nikah, and cash in a card is the norm. If the couple has a registry or cash fund, use it. The only thing to avoid is alcohol, which isn't appropriate at any part of a Muslim wedding.