[Kindred]

pawn Код:

CMD:message(playerid,params[])
{
    new messagetext[128], string1[128];
    if(sscanf(params, "s[128]", messagetext)) return SendClientMessage(playerid, -1, "Usage: /message [text]");
    format(string1,sizeof(string1),"%s",messagetext);
    return 1;
}

I'll explain it a bit. The sscanf checks if the params of the command is a string, of which is the messagetext, and if not, it sends a message saying how to use it. If it is, it continues, obviously, and formats it into a string. Thats all I wrote on there, considering you didn't explain what else you wanted in there, such as a playerid or something.

Hope I helped (this should work, didn't test, but no warnings/errors in compile).