The other day a friend and myself were waiting for someone near a subway station. The two people we were waiting for were late by quite a bit. While waiting, we decided to count 70 excuses for the people being late. Making 10 excuses was easy, but it was struggle after that and we were having to be very creative. By the time we got to 21, the individuals we were waiting for arrived. It turned out one of the excuses we made was actually true. The struggle to make so many excuses made one reflect on how much benefit of doubt one has to give other people. The teaching of making 70 excuses is sourced from what follows:
Hamdun al-Qassar, one of the great early Muslims, as narrated by Imam Bayhaqi in his Shu`ab al-Iman [7.522] said: exercise
"If a friend among your friends errs, make seventy excuses for them. If your hearts are unable to do this, then know that the shortcoming is in your own selves[ibid]"
This is because the default assumption about all humans and their actions is that they are sound and free of error. This is considered our operating certainty.
After this, if we find something that makes us doubt about them, we are not permitted to leave this operating certainty that they did not err for mere doubts or misgivings.
Allah Most High commanded us:
"O you who believe! Shun much doubt; for lo! some doubt is sinful." [Quran, 49.12]
The doubts and misgivings about others that are sinful are those that do not have a sound basis that would be sufficient to leave our operating assumption about others that they are upright and their actions free of error.