משנה אויף רות 2:14

Greater stringency applies to sacred things than to terumah, that they may immerse vessels within vessels [together] for terumah, but not for sacred things. The outside and inside and handle [of a vessel are regarded as separate] for terumah, but not for sacred things. One that carries anything possessing midras-uncleanness may carry [at the same time] terumah, but not sacred things. The garments of those who eat terumah posses midras-uncleanness for [those who eat] sacred things. The rule [for the immersion of garments] for [those who would eat terumah is not the same as the rule for [those who would eat] sacred things: for in the case of sacred things, he must [first] untie [any knots in the unclean garment], dry it [if it is wet, then] immerse it, and afterwards retie it; but in case of terumah, it may [first] be tied and afterwards immersed.

One who finds tefillin should bring them in one pair at a time. Rabban Gamaliel says: two pairs at a time. To what does this apply? To old ones but in the case of new ones he is exempt. If he found them arranged in a set or in bundles he shall wait by them until it is dark and then bring them in. In a time of danger, he should cover them and walk away.