The verse says “And you should be guarded very well for your souls!” and it also says “Only guard yourself and look very well after your soul!”. Look and see that in no other commandment does it say the word “Me’od” (meaning very well) as it does in this commandment as a person is obligated to guard his soul from all danger and even a possibility of danger. The reason that the Torah insisted so much on this is that “one hour of Torah and good deeds in this world is better than the entire life in the next world!”, and therefore one who makes himself enter into dangerous situations will possibly destroy his entire life in this world and will therefore be unable to fulfil the commandment and come to life in the net world. Chazal said that “A person should never bring himself into a dangerous situation as maybe a miracle will not be done for him. Even if a miracle is performed for him, they will deduct it from his merits!”.
The Talmud (Tractate Berachos 32b) relates that a certain pious man was standing in prayer and a non-Jewish prince met him and greeted him and he did not reply. The prince waited until he had finished his prayer. After he had finished his prayer the prince said to him “Empty person! Does it not say in your Torah that you must guard your lives very well? When I greeted you, why did you not greet me in return? If I would have decapitated you with my sword, who would have held me to account for your murder?”. The pious man answered him, “If you would be standing before a king of flesh and blood and a friend of yours would come and greet you, would you return that greeting?”, and the prince answered him “No!”. The pious man continued and asked “And if you would have returned the greeting, what would have happened to you?”, to which the prince replied “They would have decapitated me with a sword!”. The pious man said to him “Is there not a logical argument here? If already you who if you would have been standing before a king of flesh and blood who is here today and tomorrow will be in the grave you would have received this punishment, I, who was standing before the supreme King of the kings of all the kings, the Holy One Blessed be He who lives and exists forever and ever, how much more so may I not interrupt to answer your greeting!”. The prince was immediately appeased and the pious man returned home in peace. Some of the commentators explain that on the contrary, the pious man was taken to his eternal resting place as a punishment for having transgressed the prohibition of “And you should be guarded very well for your souls!” because he should have worried that the prince would kill him and he should therefore have returned his greeting in the middle of his prayer and not rely on being able to appease him with words afterwards.
We see from here that a person who puts himself into a dangerous situation and relies on miracles does two evils to himself. One is that he will be punished for having transgressed the prohibition of “And you should be guarded very well for your souls!” and the second is that they will deduct from his merits and he is like someone who swaps a pearl or other precious stone for something worth only a Perutah (smallest denomination of coin in the days of the Talmud). It follows that it is fitting for a person to guard his life very well from all possibilities of danger and he should not go on journeys or enter the seas or rivers unless there is a great need and definitely not for a small amount of money. Any money which he spends to guard his life and not to enter a dangerous place is considered spending money on a great Mitzvah.