It is narrated from Sayyiduna Salman bin Amir (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "When any of you breaks his fast, he should break it with dates; if he does not find dates, then with pure water, for water is pure."
In this hadith, there is an instruction to break the fast with dates, and this instruction or command is for recommendation (istihbab). If dates are not available, then the fast can be broken with water or any other thing. However, breaking the fast with dates is recommended (mustahabb).