If a perfected Sheikh sees that something seriously heavy is written in the destiny of a disciple, he does not delete it but he may intervene in order to attenuate it: he affixes a sign in the spiritual world so that the student will not have a lethal accident, but he will be only slightly wounded for example.
The master can not completely erase the event, because there is a limit in the influence that can be exerted on what it is written. If he would interfere in the matrix stopping completely the accident, then this would jump on someone else. This applies also in the positive, for the blessings. If a saint performs miracles, he will not be able to do it for long, otherwise the history would be rewritten.
Each Sheikh has powers that allow him to perform miracles. It is not difficult. But he knows that if he would use them too much, he would cause big imbalances able to shake the higher arrangements.
For this reason, the Naqshbandi masters prefer to use rarely the powers at their disposal: they do it only when necessary and after making sure that no one could ever know or can assign them to them.
The founder of our order, Shah Bahauddin Naqshband (may his secret be sanctified) said: “A Naqshbandi Sheikh can be skinned, but he never show his powers.”