Here Jesus teaches us that if we have unwavering and unchanging (mustard seed) faith we can say and then receive manifestation. The question arises: how do we build unwavering and unchanging faith? We build it by continually speaking aloud, and therefore, hearing The Word of God - written and spoken. Continually.
Jesus spoke and had guaranteed manifestation because He spoke The Word and had perfect faith. He's The Author and Perfecter of our faith so if we continually speak and hear His Words - written and spoken because prophetic words are valid - our faith gets perfected and manifestations will come.
Jesus said if I have faith I can say and receive. I have faith from God and I say by Christ's wounds I'm healed and walk in healing and divine health all the days of my life. I've been redeemed from the curse and am a new creation with the very DNA of God running through my veins. I'll live and not die and declare God's Glory. Amen.