What is the first divorce pronouncement (ṭalqa), how does it occur, and what obligations follow for the spouses to resume their marital life?

The first divorce (ṭalāq) is that which has not been preceded by any divorce. It occurs when the husband pronounces a clear divorce or an ambiguous one coupled with the intention. The prescribed manner is for it to occur during a period of purity (ṭuhr) in which no intercourse has taken place. The divorced wife observes her waiting period (ʿiddah) in her husband's home, and her maintenance is obligatory. It is permissible for him to be alone with her and to take her back during the waiting period either by word or by intercourse. These rulings apply to a wife with whom intercourse has occurred. As for a wife before intercourse, she becomes irrevocably separated from him by a single divorce, and she does not become lawful for him again except through a new marriage contract.