Is raising the index finger upon completing tasbeeh, tahmeed, and takbeer established when saying "La ilaha illallah"?

Tasbeeh (glorifying Allah), Tahmeed (praising Allah), Takbeer (magnifying Allah), and Tahleel (declaring Allah's oneness) after prayers are a confirmed Sunnah (definition) of the Prophet, peace and blessings be upon him, and they carry immense reward. Among these is what Muslim narrated from Abu Hurairah that the Prophet, peace and blessings be upon him, said: (Whoever glorifies Allah thirty-three times after every prayer, and praises Allah thirty-three times, and magnifies Allah thirty-three times, making a total of ninety-nine, and then completes the hundred by saying: 'There is no god but Allah, alone without partner, to Him belongs sovereignty and to Him belongs praise, and He is over all things competent,' his sins will be forgiven, even if they were like the foam of the sea). As for raising the index finger when performing Tahleel in this specific instance, it has not been proven in the Sunnah.