Function transfer 

pub fn transfer(
    token_program_id: &Pubkey,
    source_pubkey: &Pubkey,
    destination_pubkey: &Pubkey,
    authority_pubkey: &Pubkey,
    signer_pubkeys: &[&Pubkey],
    amount: u64,
) -> Result<Instruction, ProgramError>

👎Deprecated since 4.0.0:

please use transfer_checked or transfer_checked_with_fee instead

Creates a Transfer instruction.