Assalaam alaikum warahmatullahi wabarakatuhu.
As I know cleaning our teeth by miswak is very beneficial for our health wise and also it is the sunnah of our beloved prophet SAW.
Recently some one told me this. By doing miswak before perfoming ablution (wudhu) will make you remember Kalima (LAILAHA ILLALLAHU MUHAMMADUR RASULULLAH) at the time of dying. Is it true? please guide me.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Some Muslim jurists mentioned that among the benefits of using Siwaak is that it will make the Muslim remember the two testimonies of faith at the time of death. After research, however, we did not find any Hadeeth supporting what they mentioned. Certainly, this matter cannot be confirmed except with a clear text; there is no room for reasoning or Ijtihaad in this respect. For further information about the merits of Siwaak, see Fatwa 91603.