What is the standard that determines the sufficiency of exerting means for reliance upon Allah (Tawakkul), and is "tethering a she-camel with an iron chain" considered an exaggeration in employing means or not?

Taking means does not negate reliance on Allah; rather, it is something enjoined by the Sharia, coupled with the belief that harm and benefit are in Allah's hands. It is stipulated that there must be a real connection between the cause and the effect, and that the cause must be legitimate. The servant should be moderate in taking means: he should neither neglect them entirely nor let his heart become attached to them. Instead, he should use them as a means, while his heart remains attached to the Creator. Ibn Taymiyyah said: "Turning to a means means the heart's reliance on it, its hope in it, and its dependence on it. There is nothing among creatures that deserves this, because it is not independent." The guideline for taking means varies according to the thing; thus, precautions for a mild illness differ from those for a severe one, and safeguarding something valuable differs from safeguarding something insignificant, and so on.