Is a divorce that occurred via text message considered an irrevocable divorce, and what are the implications of that in terms of the waiting period (iddah) and expiation (kaffarah), and is it permissible to take the wife back via text message without witnesses?

Writing down an explicit divorce pronouncement effectuates divorce if the husband intends it. The number of repeated pronouncements depends on the husband's intention: if he intended emphasis, only one divorce occurs; otherwise, three occur. Sheikh al-Islam Ibn Taymiyyah holds the view that only one divorce occurs regardless of the husband's intention. If one divorce occurs, reconciliation is valid through writing and intention, even without witnesses or the wife's knowledge. However, if three divorces occur, she does not become lawful for her husband until after another valid marriage, followed by divorce or death, and the completion of her iddah (waiting period). If a woman abandons mourning until her iddah expires, there is no expiation upon her. It is recommended to present the matter to a Sharia court or to trustworthy scholars.