Before opening the mouth with any word, it is recommended to say the following prayer after the Dawn (Fajr) Prayer so that all sins committed throughout the week will be forgiven:
 
O Allah, whatever saying I have uttered this week, whatever oath I have taken during it, and whatever vow I have made during it, verily, it is Your will that is before all that. Hence, only that which You will to have effect will come to pass and whatever You do not will to have effect will never come to pass. O Allah, (please) forgive me and overlook my offenses. O Allah, whosoever You bless, then I invoke Your blessings upon him and whosoever You curse, then I invoke Your curse upon him.
 
Shaykh al-Tusi has recorded that it is highly recommended to say the following prayer after the Dawn Prayer on Fridays:
 
O Allah, I am resorting to You with my needs, and I am putting in Your presence my poverty, my indigence, and my deprivation. Verily, I hope for Your forgiveness more than I rely on my deeds. Indeed, Your forgiveness and Your mercy are more inclusive than my sins are. So, (please) embark on settling all my needs out of Your power over them, out of the easiness for You to do that, and out of my urgent need for that. Verily, I have not gained any good thing save from You and none could ever repel evil from me save You. I hope for none to stand for me in my affairs of this world and the Next World and on the day of my poverty, when people will leave me alone in my hole (i.e. grave) and I will then confess of my sins before You, except You.