After a woman has been irrevocably divorced by the triple talaq, the Quran states she is not lawful for her former husband again until she marries another man in a genuine marriage; if that second marriage then ends naturally (through his death or his own free divorce), she may remarry the first. Halala (nikah al-tahlil) is the sham of arranging a temporary 'marriage' with a second man for the sole purpose of making her lawful again for the first husband, and this is emphatically forbidden. The Prophet (peace be upon him) cursed the muhallil — the man hired to marry and divorce her — and the muhallal lahu, the first husband for whom it is done. A contract entered with a secret intention to divorce is invalid and does not make the woman lawful for her first husband.
Q&A · Marriage & Divorce
What is halala (tahlil) marriage, and is it permitted?
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.