Musannaf Ibn Abi Shaybah 26047 — Licking the fingers

It is narrated from Ibn Uyaynah that he said: I said to Ubaydullah bin Abi Yazid: Did you use to attend the meals of Sayyiduna Ibn Abbas (may Allah be pleased with them both)? He said: Yes. I asked: What did you see him doing? Ubaydullah said: I used to see him licking his three fingers.