Hazrat Abu Thamamah (may Allah have mercy on him) narrates that I met Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him) while I was going for Jumu'ah and I had interlaced my fingers with each other. When I got close, he struck my hands and separated my fingers and said: Indeed, we have been forbidden from interlacing our fingers during prayer. I said: I am (still) not in prayer. He said: Have you not performed ablution and do you not intend to go for Jumu'ah? I said: Yes (that is the case). He said: Then you are already in prayer.