Hello Sumu
When a router is enabled with OSPF, it sends hello packets outside ALL of its network interfaces by default regardless of which subnets are participating in OSPF, regardless of which subnets are included in the network command.
The statement
“All interfaces that have a network that falls within the range of the network command will be advertised in OSPF”
means that the advertisements that are sent will include information about these networks. This means that by default, hello packets will be sent on all interfaces including Fa0/0 and Fa0/1 and will contain only information about networks configured with the network command. This is why the passive configuration must be employed on the Fa0/1, because hellos will be sent from there even though there is no router connected to this port.
I hope this has been helpful!
Laz