Here is what i found in malik's muwatta
malik's muwatta:
book 3, number 3.13.51:
Yahya related to me from Malik from Muslim ibn Abi Maryam that AIi ibn Abd ar-Rahman al-Muawi said, "Abdullah ibn Umar saw me playing with some small pebbles in the prayer. When I finished he forbade me, saying, 'Do as the Messenger of Allah, may Allah bless him and grant him peace, did.' I said, 'What did the Messenger of Allah, may Allah bless him and grant him peace, do?' He said, 'When he sat in the prayer, he placed his right hand on his right thigh and he closed his fist and pointed his index finger, and he placed his left hand on his left thigh. That is what he used to do.' "
Here is what is written in Sahih Muslim:
Sahih Muslim:
book 004, number 1201:
Abdullah b. Zubair narrated on the authority of his father: When the Messenger of Allah (may peace be upon him) sat in prayer. he placed the left foot between his thigh and shank and stretched the right foot and placed his left hand or his left knee and placed his right hand on his right thigh, and raised his finger.
book 004, number 1202:
Abdullah b. Zubair narrated on the authority of his father that when the Messenger of Allah (may peace be upon him) sat for supplication, i. e. tashahhud (blessing and supplication), he placed his right hand on his right thigh and his left hand on his left thigh, and pointed with his forefinger, and placed his thumb on his (milddle) finger, and covered his knee with the palm of his left hand..
book 004, number 1203:
Ibn 'Umar reported that when the Messenger of Allah (may peace be upon him) sat for tashahhud he placed his left hand on his left knee. and his right hand on his right knee. and he raised his right finger, which is next to the thumb, making supplication in this way, and he stretched his left hand on his left knee. Another version on the authority of Ibn Umar says: When the Messenger of Allah (may peace be upon him) sat for tashahhud, he placed his left hand on his left knee and placed his right hand on his right knee, and he formed a ring like (fifty-three) and pointed with his finger of attestation.
book 004, number 1204:
'Ali b. 'Abual-Rahman al-Mu'awi reported: 'Abdullah b. Umar saw me playing with pebbles during prayer. After finishing the prayer he forbade me (to do it) and said: Do as the Messenger of Allah (may peace be upon him) used to do. I said: How did Allah's Messenger (may peace be upon him) do? He said that he (the Messenger of Allah) sat at tashahhud, placed his right palm on the right thigh and closed all his fingers and pointed with the help of finger next to the thumb, and placed his left palm on his right thigh.
those who move the finger say it is to ward of devils. but that doesn't make sense to me. those who point with the finger say that the finger of shahada is raised to testify that "there is no god but Allah" during the tashhud, which seems more reasonable. after all tashhud is a position where you give the shahada.