Unfortunately there is nothing you can say to him that will make it easier on him. The only job you have is to be there for him. Listen to him when he needs to talk about it, cry with him when he needs to cry, and do nothing for him when he just wants to be alone. Losing my father was the one thing that brought me to my knees. It was also a time when I was in a crowd but I was alone. After the funeral you go through what I call the leper stage, this is when you meet people you know when you are out in public and noone wants to talk to you about your dad, yet they choose not to because they don't want to upset you. The best thing you can do for your husband is to not preasure him to get over it. It can take days, months or even years for some people to stop grieving, I being there for him when he needs you is all you can do.
I agree wtih litsey. You need to give him time. I find that men have a much more difficult time grieving because they want to always appear strong and consider crying and grieving a "weakness". Women just let loose anywhere! (I know that I did). When I look at the date, I can see it was just before the holidays. The holidays (especially the first year) are very very difficult. Many memories which will someday be so special are sooo extremely painful in the beginning.