Analogue to has_many :through

Let's say i have three models: user, message, picture. User has many
messages and pictures, picture belongs to user, message belongs to
user. Now if i want to get pictures of author of specific message i
call message.user.pictures. However this means i get two queries to
database 'select * from users where id = [message.user_id] limit 1'
and 'select * from pictures where user_id = [user.id]'. But is there
any way to force only one query 'select * from pictures where user_id
= [message.user_id]' except for pictures = Picture.all(:conditions =>
{:user_id => message.user_id}) ?

how about:
Message.user.find(:all, :include => :pictures)
i might be wrong

Message has only one user. Tried message.user(:include => :pictures)
but it didn't work.