Hazrat Sha'bi (may Allah have mercy on him) said: If someone gives his wife three divorces and accuses her during the waiting period, then he will perform li'an during the waiting period. If the waiting period ends, then the prescribed punishment will be carried out and li'an will not take place.
Hadith Referenceسنن سعید بن منصور / كتاب الطلاق / 2751
Hadith Takhrij«أخرجه سعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم:، 1573، وابن أبى شيبة فى «مصنفه» برقم: 29453»