Ibn Sirin (may Allah have mercy on him) said that a man claimed a right against someone and also presented a witness. Qadi Shurayh asked him to swear an oath, and it was as if he was refusing the oath. So the judge said: What a poor commendation you are giving your witnesses!
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الدعوى والبينات / 21249