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A sick person has a mitzvah to go to a doctor, but he also has an obligation to pray to Hashem, who heals all flesh, that he give a berachah and Divine assistance to the doctor that he will successfully treat and provide the appropriate medicines that are suitable for him. Likewise, a person must be concerned with his livelihood, with prayer from the depths of his hearth to his Creator that He give a berachah on his actions and makes his business succeed. Similarly, all the fruit and vegetables that we need, only grow after the farmer ploughs the land and sows the seeds, and only after that the rain and sun which come from Hashem bring the berachah and success for the fruit and vegetables to grow. But if the rain were to fall all day and night, and the farmer didn’t sow, then nothing will happen. This is to teach us that Hashem Created His world in such a way that a person shall do what is required of him and only then through belief and prayer will Hashem give His berachah for success and abundant blessing.