Bismillahi Al-Rahmani Al-Rahim
Some of the evidence that Hanbalis use to support this is by collecting the hadiths concerning this subject, and then using them to explain one another. Sticking to short books: Manar al-sabil lists two hadiths:
And the author of Al-Salsabil fi ma`rifat al-dalil adds that Al-Bayhaqi mentioned this hadith. The author then adds: â€œIn accordance to the sound position from the madhhab: someone praying points with his finger without moving it, because of what Al-Bayhaqi narrates in his Sunan
Al-Bayhaqi says that it is possible that what it meant by â€œmovingâ€ [tahrik] is pointing with it, not repeatedly moving it, and thus being in agreement with the hadith of `Abd Allah bin al-Zubayr. (Sheikh Salih bin Ibrahim al-Balayhi, Al-Salsabil fi ma`rifat al-dalil, 1.126 fn 29).
And Al-Buhuti in Al-Raud al-murbi` mentions that the finger is pointed without being moved, and that it is done during supplication during and outside of prayer, and whenever the greatest name of Allah is mentioned. He adds that this is done tanbihan `ala al-tawhid: as a notification or reminder of tawhid. (Al-Buhuti, Al-Raud al-murbi`, p72).
This, in sha Allah, is enough evidence to give a brief survey of the evidence involved and how the Hanbalis interpret it.
As for the second part of the question, on where the finger is raised, the following texts indicate those places using red-bold.
The tashahhud: Al-tahiyyatu lillah wa al-salawatu wa al-tayyibat, al-salamu `alayka ayyuha al-nabi wa rahmatu llahi wa barakatuhu, al-salamu `alayna wa `ala `ibadi llahi al-salihin, ashhadu an la â€˜ilaha â€˜ill allah, wa ashhadu anna muhammadan `abduhu wa rasuluhu
The final supplication: Allahummasalli `ala muhammadin wa `ala â€˜ali muhammadin ka ma salayta `ala â€˜ali ibrahima innaka hamidun majid, wa barik `ala muhammadin wa `ala â€˜ali muhammadan ka ma salayta `ala â€˜ali ibrahima innaka hamidun majid.( Note: Allahumma is a phrase meaning ya Allah! [â€œO, Allah!â€]).
And Allah knows best.
Wa al-salamu `alaykum,