Can one pray istikhaarah with just one rak‘ah?
Question

                Can one pray istikhaarah with just one rak‘ah?.
Praise be to Allah.
    What appears to be the case is that the Sunnah of istikhaarah 
    cannot be done by praying just one rak‘ah, because of the report narrated by 
    Jaabir ibn ‘Abdullah (may Allah be pleased with him) who said: The Messenger 
    of Allaah (peace and blessings of Allaah be upon him) used to teach his 
    companions to make istikhaarah in all things, just as he used to teach them 
    soorahs from the Qur’aan. He said: ‘If any one of you is concerned about a 
    decision he has to make, then let him pray two rak‘ahs of non-obligatory 
    prayer…

    Narrated by al-Bukhaari, 1166. 

    Al-Bujayrami (may Allah have mercy on him) said: The words of 
    the Prophet (blessings and peace of Allah be upon him) referring to two 
    rak‘ahs of istikhaarah indicate that it cannot be done with just one rak‘ah.

    End quote from Tuhfat al-Habeeb ‘ala Sharh al-Khateeb, 
    1/428 

    Al-‘Ayni (may Allah have mercy on him) said: The evidence 
    indicates that the Sunnah in istikhaarah is to pray two rak‘ahs, therefore 
    one rak‘ah is not acceptable for istikhaarah.

    End quote from ‘Umdat al-Qaari’ Sharh Saheeh al-Bukhaari, 
    11/385 

    Ash-Shawkaani (may Allah have mercy on him) said: The words 
    “let him pray two rak‘ahs” indicate that the Sunnah in istikhaarah is to 
    make it two rak‘ahs, so one rak ‘ah is not acceptable.

    End quote from Nayl al-Awtaar, 3/88.