I read that there is a way to mourn and a length of time to mourn and that you should not mourn or grieve to the point of poverty. Where is that located in the bible?
The Bible mentions several mourning periods, differing from culture to culture. The Egyptians mourned for Jacob seventy days (Genesis 50:3). The Jews mourn for seven days, based perhaps on Genesis 50:10. Most of the time the number of days of mourning is not mentioned.
Mourning customs also varied from culture to culture. Some nations cut themselves in mourning, although the Jews were forbidden to do so (Deuteronomy 14:1). Some people tore their clothes in mourning, a practice still performed by the Jewish people. Others wore burlap and poured ashes on their heads.
Christians are not given any specific method or time to mourn. Each person mourns in his own way and for his own time.
I know of no specific scripture that says you should not mourn or grieve to the point of poverty, although that is common sense.