You can not specify the password from the command line but you can do either using ssh keys or using sshpass as suggested by John C. or using a expect script.
To use sshpass, you need to install it first. Then
sshpass -f <(printf '%s\n' your_password) ssh user@hostname
instead of using sshpass -p your_password. As mentioned by Charles Duffy in the comments, it is safer to supply the password from a file or from a variable instead of from command line.
BTW, a little explanation for the <(command) syntax. The shell executes the command inside the parentheses and replaces the whole thing with a file descriptor, which is connected to the command’s stdout. You can find more from this answer https://unix.stackexchange.com/questions/156084/why-does-process-substitution-result-in-a-file-called-dev-fd-63-which-is-a-pipe