Amr bin Shu'ayb (may Allah have mercy on him) said that Sayyiduna Abu Bakr (may Allah be pleased with him) gave judgement concerning the tongue: when it is cut off completely there is the full diyah for it, and if a little of it is cut off and speech is not stopped, there is half the diyah for it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16255