My husband has a buisness and is going to sue a former friend.

Hearsay can be brought up in court.  If not objected to it is admissible.  There are many exceptions to the rule, so even if object to, a court can, in some circumstances, still allow it.  So, you should take care.  Plus, what you say can lead to non-hearsay forms of evidence.  For example, if you say your husband cheats on his prices, that is probably hearsay.  But it will lead the other side to evidence that he cheats on prices.