Am I sinful for having shunned a colleague at work who bore false witness against me, for more than three days?

The prohibition of a Muslim forsaking his brother for more than three (days) is authentic. Repentance is obligatory for forsaking beyond the period allowed by Islamic law, which is three days, because it is generally expected that the reason for the forsaking will dissipate within this period. Forsaking for more than three (days) is permissible only if the person is openly committing a sin, and if forsaking him brings a benefit towards him abandoning that sin.