Mutual collaboration plays a vital role in sharing of resources in an ad hoc network of handheld devices in a pervasive computing environment. Effective sharing of resources is facilitating tiny pervasive devices to benefit from situations which otherwise would not have been possible due to several limitations (such as poor storage and computational capability). An unavoidable consequence of this aspect is opening the door for security breaches. Trust is the weapon which is used to fight against security violations by restricting malicious nodes from participating in any interaction. Here, we present a context specific and reputation based trust model along with a brief survey of current trust models. To the best of our knowledge, our model is the first formal omnipresent trust model for pervasive computing, which can be used universally. This paper presents a recommendation protocol that provides a multi-hop recommendation capability and a flexible behavioral model to handle interactions. This paper also illustrates the implementation and evaluation of the omnipresent formal trust model.