It is obligatory to
refrain from engaging in any transactions involving Riba or Gharar (uncertainty) such as insurance operations. Rather, a person should observe the means that do now have unlawful transactions, such as dealing in buying and selling available and lawful goods, or selling on credit, Salam sale (sale with advance payment), and working in the field of construction for individuals or companies that do not entail what you have mentioned. Whoever fears Allah (Exalted be He), is sincere in their dealings and looks for their lawful means, Allah (Exalted be He) will provide them with sustenance from places where they could not imagine. (Part No. 13; Page No. 301) Allah (Glorified be He) says:
And whosoever fears Allâh and keeps his duty to Him, He will make a way for him to get out (from every difficulty).
And He will provide him from (sources) he never could imagine.
Allah (Exalted be He) also says:
...and whosoever fears Allâh and keeps his duty to Him, He will make his matter easy for him.
It is worth mentioning that there is no harm in obtaining a bank guarantee as long as the bank does not demand interest or grant the guarantee because of its trust in the beneficiary, the mortgaged property, or the surety.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.